In different cultures or religions, people pay special attention to some specific numbers. For example, numbers 7, 40, and 70 are amongst lucky numbers, and number 13 is known to be a cursed number in some cultures. However, the significance of the number 40 among many cultures and religions is very noticeable. Therefore, this question may arise that what is so special about this number? Can number forty bring luck and happiness to people? Is it a fact or just a superstition? Let’s have a quick look at the background of the number forty in different religions.

Number Forty in Christianity 

Number forty has been mentioned in the Bible in different verses:

1- Jesus (PBUH) fasted "forty days and forty nights" in the Judean desert. (Matthew 4:2, Mark 1:13, Luke 4:2).

2- Forty days was the period from the resurrection of Jesus to the ascension of Jesus (PBUH). (Acts 1:3).

3- Rain fell for "forty days and forty nights" during the Flood (Genesis 7:4). [1] 

Number Forty in Islam 

Number forty is mentioned in the Quran four times: 

1 & 2- Prophet Moses (PBUH) spent 40 days on Mount Sinai, where he received the ten commandments (2: 51, 7: 142).

3- Prophet Moses (PBUH) and his people were lost in the desert for forty years. (5: 26)

4- As mentioned in the Quran, It seems that the age of forty should be the time when a human being is supposed to reach his/her intellectual perfection and understanding of life. This is the time when one can plan the rest of his/her life in a way to gain the most from this world for the hereafter:

“… When he comes of age and reaches forty years, he says, ‘My Lord! Inspire me to give thanks for Your blessing with which You have blessed my parents and me, and that I may do righteous deeds which please You, and invest my descendants with righteousness. Indeed I have turned to you in penitence, and I am one of the Muslims.” (46: 15) 

It is narrated from Prophet Muhammad (PBUH & HP) that “When one becomes forty years old, Allah tells his two guardian angels, ‘From now on, be strict on him and note every small and big deed he does’” [2]. The narration emphasizes that the age of forty shapes the personality of a person, and if he/she is still unable to manage his/her life, it is his/her fault for having wasted his/her life in the wrong way. 

Number Forty in Narrations and the Conduct of Scholars

There are so many narrations from Prophet Muhammad (PBUH & HP) that mention number forty. Here we list a few of these narrations:

1- “He who purifies his faith for Allah for forty days, Allah will flow the springs of wisdom from his heart to his tongue” [3].

 2- “The prayers of the one who drinks wine are not accepted for forty days unless he repents” [4] [i].

 3- “The prayers of a person who gossips would not be accepted for forty days and nights” [5].

Some scholars say that number forty is used to emphasize the significant amount of something.

4- “One who leaves his house to gain a gate of knowledge by which he deviates the wrong towards righteous, or deviance to guidance, his deed is equal to forty years worship of a worshipper” [6].

The Fortieth Day after Burial (Arba’een)

In some cultures, it is a tradition that forty days after a passed-away person’s burial, close relatives and friends gather in a place with the family of the late person and remember the passed-away person and wish peace and patience for his/her family. In this manner, they show the family of the deceased person that they are not alone, and people will help them and support them when required. 

It is based on this tradition, taken from the conduct of the Prophet (PBUH & HP) and his Progeny (AS) that Muslims travel to Karbala on the 40th (Arba’een) martyrdom commemoration of Imam Hussain (AS) and his companions; Not only to sympathize with the household of Prophet (PBUH & HP) on this event, but to show their gratefulness for their courage in preserving the true Islam and the conduct of the Prophet (PBUH & HP). More importantly, Muslims show that the aim of Imam Hussain (AS) is still observed and taken care of. 

Is It OK to Follow the Rules Related to Number Forty? 

Based on the importance that some verses of the Quran and narrations of the Prophet (PBUH & HP) give to number forty, Muslim scholars, especially those who are fond of Islamic mysticism and self-purification, pay special attention to number forty in their conducts and life-style. 

Therefore, there is nothing wrong with trying to benefit from the blessings that the number forty may have. And it is trustworthy because Allah and the Prophet (PBUH & HP) have mentioned it. However, normal human beings do not have a real knowledge of numbers and the wisdom behind them. 

A Logical Interpretation 

As mentioned in a narration earlier, the Prophet (PBUH & HP) says that if you purify your faith for forty days, you will see a great result. [7] The reason is that if one works so hard on his/her spirituality to be able to purify his faith for forty days, it will become a habit for him. Allah says in the Quran, “Be wary of Allah, and Allah will teach you, and Allah has knowledge of all things” (2: 282), which is very much relevant to the mentioned narration. Therefore, one interpretation of doing something for forty days is that whatever you do for this long period, with persistence, will become your habit, and after something becomes a habit, you can easily go on with it for the rest of your life.

Conclusion 

To sum up, there is no such thing as lucky or cursed numbers. And instead of trying to find luck in numbers, one should work hard to develop his personality, spirituality, knowledge, and wisdom. 

But the reason number forty has been mentioned by the Prophet (PBUH & HP), and Islamic scholars might be a symbol of enormousness, meaning that if you persist in doing something for a considerable amount of time, it will become your habit. However, the reason why they insisted on number forty might be because they wanted to spread unique conduct and a specific discipline among the believers. 

Notes:

[i] Some may think that if praying and fasting are not accepted for forty days after drinking, then it will be OK if they do not pray or fast for forty days after they drink. It should be noted that praying and fasting are still compulsory for the person who drinks. However, the sin is counted so huge that they should repent from it, deciding not to commit it again, and say their prayers and perform fasting and other obligations.

References 

1. number in religion
    Al-kafi, Vol 8, P. 108
    Bihar al-Anwar, vol. 67, p. 242
    Mustadrak al-Wasa’il, vol. 17. P. 57
   Al-Kafi, Vol. 6, p. 400
    Amali- e Tousi, p. 118
   Bihar al-Anwar, vol. 67, p. 242
2.  

Let's start our topic with a question. What is the meaning of 'special' in your life? What days have been special to you, your family, or even to your community? The answer may vary from mere personal occasions like birthdays, anniversaries, etc. to more public ones such as New Year's Eve, Easters, or any National Day. The same is true about every religion, culture, or society. Different days of the year have different meanings in every religious community; such as Laylatul Qadr for Muslims. 

Everything that the Almighty God has created is Noble

 "(He) Who perfected everything which He created" (Quran 32:7) 

 "…So whichever way you turn, there is the face of Allah! Allah is indeed all-bounteous, all-knowing." Quran (2:115)

"There is nothing in existence but beauty, for God created the cosmos only in His image, that is, in the image of His infinite beauty." Ibn Arabi [i], [1]& [2].

This does not, however, mean that all creatures are the same! Can river stones be equal to those of precious pearls in the oceans? The world is the world of differences, and that actually makes it delightful and adventurous. This is also manifested in people's different languages and colors, which is a sign of Allah's balanced and sophisticated creation.  

"And of His signs is … the diversity of your languages and your colors. Indeed in that are signs for those of knowledge" (Quran 30:22)

If every stone were like a pearl would have the pearl had the same value that it has now? How about the days of the year? God is indeed in All Days, but again this is God's plan for us to value specific days or nights more than others. The Islamic Holy scripture refers to a night that has the value as equal to a thousand months, called Laylatul Qadr, the Night of Decree. Likewise, the month of Ramadan or that of Dhul Hijja has special significance in Islam during which distinct rituals and etiquettes are prescribed for Muslims.  What is it that really makes them unique? For that, we will have to take a look at Islamic resources. 

Which Days or Nights Are Superior in Islam?

As indicated earlier, certain nights and days are adored in Islamic culture.

In a week, Friday does not only mark the weekend, but it has a special meaning for Muslims. The Surah "al-Juma" in the Quran declares the importance of the Friday prayer that is a congregational prayer held at Friday noon, and it is also referred to as the "the pilgrimage of the poor" in Islamic traditions. 'Forgiveness of sins,' 'reduction of the difficulties in the Day of Judgment,' and 'great rewards for every step to the place of the Friday prayer' are only a scratch over the surface of the benefits of this ritual for those who attend it [3]. 

In a year, the three months of Rajab, Shaban, and Ramadan are highly appreciated. It is narrated that Prophet Muhammad (PBUH&HP) has said: "Indeed Rajab is the month of Allah, while Shaban is my month and Ramadan is the month of my community" [4]. Ramadan is the month in which the Quran was revealed to the Prophet (PBUH&HP). It is also the month of fasting for Muslims [5]. 

In a grand tradition, the Prophet (PBUH&HP) narrates that Allah (SWT) said: "Fasting is for me, and I am the one who rewards for it" [6], "The gates of the fire are closed (in this month), so ask your Lord not to open them and Satans are in chains. So ask your Lord not to dominate them over you." This month is the best month in the sight of Allah, its days are the best, its nights are the best nights and its hours are the best hours… your breath in it (the month of Ramadan) is glorification (of God), and your sleep in it is worship" [7].

The Night of Decree (Laylatul Qadr) 

Moreover, it is in this month that the Night of Decree (Laylatul Qadr) is celebrated. A night that is regarded as equal to a thousand months, and it is when humankind's destiny is decreed for the coming year. It was on this night that the Holy Quran was revealed to the Prophet [8]. Indeed, Ramadan is the best month, and the Night of Qadr (Decree) is its heart. Believers stay awake the entire night and pray for blessings and forgiveness. It is the holiest night of the year, and it would be unwise to be heedless of the tremendous benefits of this night. It is a grand opportunity that God has gifted us with; there is a night that our whole year is decreed and if praying that night, we can ask Him to bless us with a year full of the happiness, the spirituality, the health and the success and whatever good we want in our lives. That's how God gives us the chance to rebuild our destiny, and a new beginning of our spiritual calendars, to ask forgiveness for the sins we have committed in the past year while praying for a better fate in the coming year.

The above briefly indicates how some days, months, and nights are special in Islam. The question now remains how we are going to use them and benefit from them.  When we are invited to such a special feast undoubtedly, we have to get prepared and plan for it; otherwise, we gain nothing but regret.

That's the beauty of having faith. Your days and nights are not equal. Each and every one of them has their own distinct meanings. It makes the spiritual journey of a servant sweeter and more enjoyable. He/she has always something to do to get closer to His Lord.

Notes:

[i] An Arab Andalusian Muslim scholar, mystic, poet, and philosopher, whose works have grown to be very influential. 

References:

1.  Claude Addas, The Experience and Doctrine of Love in Ibn Arab, http://www.ibnarabisociety.org/addas1.html 
2. William C. Chittick, The Divine Roots of Human Love,
3. divine roots
4.  Al-'Allama al-Majlisi, Bihar al-Anwar, vol. 86, p. 197, Al-Shaykh al-Saduq, Man la yahduruh al-faqih, vol. 1, p. 427, Nuri, 
5.  Al-'Allama al-Majlisi, Bihar al-Anwar, vol. 104, p. 123.
6. The Quran 2:183&5
7. Shaykh al-Hurr al-Amili, Wasā'il al-Shi'ah, vol. 10, p.400.
8. Al-Shaykh al-Saduq, Al-Amāli, p.95.
9. The Quran, Chapter 97th.