During one of his journeys, As-Sari As-Saqṭee passed by a cave, from which he heard continuous sobbing. Aroused by curiosity, he entered the cave and saw a young man whose body seemed to be wasted away by grief and sadness.
Having immediately perceived that the man was a righteous worshipper, As-Sari humbly asked, "O young man, how is safety achieved?"
He said, "By performing all prescribed acts of worship, by not wronging others, and by repenting to Allah."
As-Sari asked, "Can you please deliver a sermon to me?"
The young man said, "The best sermon you can receive is by looking into your own self. But I will say this: Be obedient to Allah when you are alone, for doing so will atone for your sins, and Allah will then display you to the inhabitants of the heavens."