Sayyiduna Mu'adh bin Anas (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "The most virtuous deed is that you keep ties with the one who cuts you off, give to the one who deprives you, and overlook the one who reviles you."
Al-Tabarani recorded it; its chain contains a narrator, Zabban bin Fa'id, who is da'if (weak).