1. The World in Jesus Christ (PBUH)'s View

This world is a bridge, pass it and don't get attached. 

Sheikh al-Mufid, Al-Amali, p.43.

2. You Reap What You Sow

Everyone is after the reward [that comes at the end], and no one will get it except through hard work. 

Mizan al-Hikma, hadith no. 22083.

3. The Lasting Lights

Good for the ones who pray at the heart of the night; those are the ones who will inherit a lasting light. 

Tuhaf al-Uqul, p.510.

4. Faithfulness in Jesus Christ (PBUH)'s View

A tree is perfected only through giving fruit, as faithfulness is only accomplished through avoiding what is forbidden (Haram). 

Tuhaf al-Uqul, p.511.

5. Beware of Your Eyes

Be careful about what you are looking at since the mere act of looking [at something inappropriate] will put the seed of desire in your heart, which would later turn into a disaster. 

Tuhaf al-Uqul, p.502. 

6. Most Cherished Ones

Good for the ones who make amends among people; those are the most cherished on the Day of Judgement.

 Tuhaf al-Uqul, p.501. 

7. Servants of This World

O' servants of the world! You are like a lamp that gives light to people and burns itself instead. 

Tuhaf al-Uqul, Hadith no.500324.

8. Modesty in Private and Public

As you present modesty and humbleness among people in public, be modest and humble with regard to God in private.

Tuhaf al-Uqul, Hadith no.500325.

9. A Fruitful Heart in Jesus Christ (PBUH)'s View

Verily, planting is only possible on arable land, not a barren one. Similarly, wisdom only grows in a humble and ready heart, not an arrogant and prejudiced one. 

Tuhaf al-Uqul, Hadith no.500332.

10. Practice Makes Perfect

Everyone looks upon the stars, but none finds his/her way using them, except the one who knows their places and how they work. Similarly, you will learn wisdom, but only the one who practices wisdom will be guided.

Tuhaf al-Uqul, Hadith no.500336.

11. Inappropriate Words' Echoes 

Any offensive and inappropriate word that you say today will be responded later on the Day of Judgement.

Tuhaf al-Uqul, Hadith no.500341.

12. Patience in Jesus Christ (PBUH)'s Words

Water puts the fire out, just as patience calms anger down.

Tuhaf al-Uqul, Hadith no.500347.

13. Perfect Faith as Jesus Christ (PBUH) Describes 

Water and soil are the determining factors for a good harvest, just as knowledge and manner are the keys to perfect faith. 

Tuhaf al-Uqul, Hadith no.500350.

14. Don't Be Just After this World 

The one who is only after this world is like a person drinking seawater; the more he drinks, the more he gets thirsty and finally will bring him death. 

Warram b. Abi Firas al-Hilli, Tanbih al-khawatir wa nuzhat al-nawazir, vol.1, p.149.

15. This World and The World that Is to Come

Jesus Christ (PBUH) said to the apostles: "As much as you get tired in this world, you will rest in the other world, and as much as you rest in this world, you'll get exhausted on the world that is to come."

Ismaiil Jawuhari Farabi, Al-Sahah, vol.1, p.225.

16. The Root of All Evil

Beware that the root of all evil lies in loving this world extremely. 

Warram b. Abi Firas al-Hilli, Tanbih al-khawatir wa nuzhat al-nawazir, vol.1, p.129.

17. Water and Fire

Loving this world and striving for the other world cannot come together in a believer's heart, as water and fire cannot be put together on a plate. 

Warram b. Abi Firas al-Hilli, Tanbih al-khawatir wa nuzhat al-nawazir, vol.1, p.131.

18. God's Friends 

If you want to be among God's friends and chosen ones, be kind to the one who does you wrong, and forgive the one who has done you an injustice, and greet the one who turns his face from you.

Tuhaf al-Uqul, p.503.

19. A Magnificent Person 

Whoever knows and brings what he knows into practice and teaches others, is considered a magnificent person in Allah's regard.

Warram b. Abi Firas al-Hilli, Tanbih al-khawatir wa nuzhat al-nawazir, vol.1, p.82.

20. The Most Wretched One

The most wretched among you is the one who is only known by his/her knowledge, not his/her deeds. 

Bihar al-Anvar, vol.2, p.52. 

Muslims commemorate the fortieth day after the martyrdom of Imam Hussain (AS) and his companions, called Arbaeen, meaning the fortieth day in Arabic. They all gather around the city of Karbala and Imam Hussain’s (AS) shrine, mourning and lamenting the unfair and cruel war between his comrades and those of Yazid Ibn Muawiyah, which led into the death of those pure men and the bondage of their families. 

This commemoration happens every year around the city of Karbala. Muslims begin to walk to Karbala from other towns. They gather together in groups to pray, and especially to mourn the martyrdom of Imam Hussain (AS).
This walk is a hard one. It takes at least three days and lots of energy and time. So, why do Muslims take that? What is the philosophy behind it? 

To answer our questions, first, let’s have a review of the history behind this walk and then move to the other aspects of this commemoration. 

1. What is the Arbaeen Walk?

The history of Arbaeen walk goes back to the first visitors of Imam Hussain (AS) after his death. On the day of Arbaeen, forty days after the tragic martyrdom of Imam Hussain (AS), Imam’s (AS) son, sister and the remaining members of his family and that of the other martyrs came back to Karbala to lament the death of their dear ones besides their graves.  

Their next visitor was Jabir Ibn Abdullah Ansari on the year 61 AH. Visiting Imam Hussain’s (AS) shrine was a tradition in Shiite culture until a short period after Morteza Anasari’s became the religious reference (Marja’) of Shiite Muslims. It was then lessened for some years and then revived. Some other religious references (Marja’) kept this tradition alive among their followers, until the government of Saddam Hussain, which banned all religious Shiite traditions to be performed publically [1]. 

The tradition was revived after the fall of Saddam, and it is still to be continued. 

2. Why on Foot?

Visiting the holy shrines and going on pilgrimages on foot is not something new or belonging to our age. It’s got a long history, and Adam did the first pilgrimage on his visit to Mecca [2]. It isn’t a tradition just among Muslims either. It is performed in other faiths and religions, too. For instance, Caesar made a vow to his God to go on a pilgrimage to the Dome of Rocks if he won the battle against the Empire of Persepolis (Iran). He performed his vow after his victory [3].

Pilgrimages are highly admired, and their act is seen as a way of getting closer to Allah by Imam Sadiq (AS). Visiting the holy shrines of the twelve Imams (AS) is even more praised, especially the sacred shrine of Imam Hussain (AS). Of course, it’s not these shrines themselves that are of value and importance, but the people who have been buried there. Thus, when one makes a pilgrimage toward these shrines, he/she finds the chance to think more about these great personalities who won Allah’s satisfaction and praise and were Muslims in the real sense of the word. So, in every step that a pilgrimage takes toward Imams' (AS) shrines, especially that of Imam Hussain (AS), he/she is getting closer to a source of spiritual blessing, bringing him/her thousands of virtues and wiping away thousands of vices from his/her mind and soul.

3. What is the Philosophy behind the Arbaeen Walk?

The Arbaeen pilgrimage is not merely a long walk. Instead, it is a kind of movement in which despite being in publics, pilgrims have their own private relationship with Allah and Imam Hussain (AS), which finds a new form of divine immaterial dependence and conformance. Thinking about the goals and the history behind the martyrdom of Imam Hussain (AS), the injustice and cruelty imposed on his family and the devotions of his faithful followers brings about many personal and social growth and improvements. 

Meeting other Muslims, exchanging ideas, and making friendships with Muslims of the other countries is another social outcome of this pilgrimage. One finds out that they are not alone in their faith, and have friends all over the world. They may have differences, but they have one thing in common: Belief in Imam Hussain (AS) and his right cause. 

The last and the most crucial point to mention this great gathering is it's a kind of preparation for the grand reappearance of Imam Mahdi (AS), the awaited savior among Muslims. The Arbaeen pilgrimage is to make the minds and souls ready for this great event. It is said that when Imam Mahdi (AS) reappears, he introduces himself as the son of Hussain (AS) [6], whose fame has reached many people through the Arbaeen Pilgrimage; one of the most significant religious gathering around the world, with the estimated number of 40,000,000 people participating in it, whose news is broadcasted all over the world [5].  

References

1. "The background of Arba'een rally/The importance of Najaf-Karbala rally from the scholar's viewpoint." Fars News. Archived from the original on 16 November 2015. Retrieved 4 October 2015.
2. Hor Ameli, Muhammad Bin Hussain Vasayel-o-Shia, Vol 11, p 132
3. Sobhani, Jafar The Light of Eternity p. 696
4. Kamel-o-Ziyarat: Pp 183, 184 and 185
5. Philipson, Alice (19 January 2015). "The ten largest gatherings in human history." The Telegraph. Archived from the original on 6 October 2015. Retrieved 3 October 2015. 
6. Khademi Shirazi, Mohammad Yad’e Mahdi P16, P132