سنن ابن ماجه

It was narrated from Mus’ab bin Sa’d that his father, Sa’d bin Abu Waqqas, said: “I said: ‘O Messenger of Allah, which people are most severely tested?’ He said: ‘The Prophets, then the next best and the next best. A person is tested according to his religious commitment. If he is steadfast in his religious commitment, he will be tested more severely, and if he is frail in his religious commitment, his test will be according to his commitment. Trials will continue to afflict a person until they leave him walking on the earth with no sin on him.’”