Whoever has offended you and then approached you to apologize, humility obligates that you accept his apology whether it is truthful or not, and that you leave his secret thoughts to Allah. The sign of generosity and humility is that if you notice a defect in his apology, you do not address it nor hold him against it.

Ibn al-Qayyim, Madaarij as-Salikeen (Ranks of the Wayfarers), 2/338. (via brotherhoodinislam)