The Prophet said:

“He whom Allah wants to show kindness to, He instructs him in the religion.”

The greatest of the gates that saves the servant from perdition is faith in Allah, and in all that He has ordered to be believed. Faith is Tawhid which constitutes Al Fiqh Al Akbar, it is the greatest of understandings in the religion. The servant therefore needs to know that his need for faith in Allah, and in all that He has commanded to be believed, is more important than his need for food and drink.

Source: Explanation of the Three Fundamentals by Cheikh ‘Abd Al Razzaq Al Badr, may Allah protect him.