Professor Ansarian:
The one who says I trust Allah must be satisfied with all the dispensations and all orders of Allah Almighty. There should be no dissatisfactions and complaints in someone who trusts Allah Almighty, because he trusted Allah, and it means he has taken Allah as his lawyer. So, this lawyer recommend them to fast, say prayers, do Hajj and Jihad and all of these are to their own benefits. I trust Allah means; oh Allah, thou art my lawyer, do whatever you know is best for me, and whatsoever is to my benefit tell me to do them.
source : erfan.ir