Professor Ansarian:
There are three classes in this universe that if a Muslim do not pass these three classes and do not attend these classes wholeheartedly and with all his attention, he is like a ripe fruit, fruitless tree and field with no crops.
The Almighty Allah has mentioned these three classes in the verses of the holy Quran especially in verse 218 of Surah Baqarah as follows:
The first class is faith
The second class is migration which is the most important class and this migration means struggling against ego and not succumbing to its demands.
source : erfan.ir
