Is seeking forgiveness, feeling remorse, giving charity, and praying sufficient for someone who returned mockery with mockery to a colleague in an online group, after the colleague became angry and threatened not to forgive until the Day of Judgment?

If a man mocks you, he has done wrong, for Islamic law forbids mockery, as Allah Almighty says: "O you who have believed, let not a people mock [another] people; perhaps they may be better than them; nor let women mock [other] women; perhaps they may be better than them."

If your response to him is with similar mockery and within the same bounds, then there is no sin upon you, for Allah Almighty says: "And whoever avenges himself after he has been wronged - those have not upon them any cause [for blame]."

However, if you exceed the limit, then you have done wrong and committed injustice. And if he does not forgive you, then you must frequently supplicate for him and seek forgiveness for him.