And the worst of brothers is he who abandons his brothers during [their time of] hardship and need.
By Allaah! Allaah has venerated the sanctity of the believer, such that He has prohibited you from assuming other than good of your brother.
From the indicators of the tenderness of a believer’s heart is that he feels pain at the mishap of his believing brother when he slips up, so much so that it is as if he himself is the one who has slipped up; and he [certainly] does not maliciously rejoice [at his brother’s lapse].
So your brother is the one who advises you, and reminds you, and warns you [against pursuing the path to desctruction].
In the absence of your brother, make mention of him with what you [yourself] would like to be remembered with, and do not make mention of him with what you [yourself] would not like to be mentioned of yourself.
What is the ruling if I see someone committing a sin, and I don’t advise him because he knows the ruling?