Mishkat al-Masabih #1482

Sa'd said that when the Prophet was asked which people suffered the greatest affliction he replied, “The prophets, then those who come next to them, then those who come next to them. A man is afflicted in keeping with his religion; if he is firm in his religion his trial is severe, but if there is weakness in his religion it is made light for him, and it continues like that till he walks on the earth having no sin.” Tirmidhi, Ibn Majah and Darimi transmitted it, and Tirmidhi said this is a hasan sahih tradition.