Among the right of brotherhood is Upon meeting your Muslim brother, call him by a name he loves and greet him with a smiling face.
The kind Prophet (PBUH) said:
“To smile at your brother is charity.” Encourage him to converse with you, or in other words, give him an opportunity to talk to you about himself and about his life. Ask him about his affairs, but only about those things that won’t cause him
The Prophet reportedly said: “Whoever is unconcerned with the affairs of the Muslims, is not from among them.”
A Qur’anic verse reads:
The believers, men and women, are Auliya [helpers, supporters, friends, protectors] of one another…) (Qur’an 9:71)
Also, neither blame nor remind him of his past errors nor should you cause him discomfort by making fun of him. The Prophet (PBUH) advised: “Do not dispute with your brother, don’t make fun of him, and don’t make an appointment with him and then not show up.”
Two secrets of sins … But commit it not!
Some learned people mentioned that:
1) After repenting from sin, one’s feelings of self-importance and sanctimoniousness are quelled.
2) Allah’s names and attributes, such as the Most Merciful and the Oft-Forgiving, bear a greater meaning for the one who sins and then repents.
And Allah knows best.
Source: Don’t be sad