There is an expression in Islamic jurisprudence called "mandatory duty".this expression is a legitimate and correct one within the framework of jurisprudence but it is not so popular and commonly accepted in mysticism. Because the task is taken from the burden. Burden means: load, heaviness.in mystics’ perspectives good deeds and specifically acts of worships are not duty and task.since carrying out such acts and practices have no hardships and difficulties for the believers.
Imam Hussain said that the Messenger of Allah has declared:
The best people are those who are lovesick of worship and they are closley related with it, and wholehearetedly be amorous and preoccupied with it and worship Allah Almighty with their body and soul as well as free thought.and for such people it makes no diffiference whether the world is rotating on hard orbit or the easy one.
source : erfan.ir
