Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) reports this saying of the Prophet (peace and blessings be upon him): "Teach, make things easy and do not make them difficult. When one of you becomes angry, he should fall silent; when one of you becomes angry, he should fall silent."
Ahmad and al-Tabarani recorded it. The narrators of Ahmad are thiqat (trustworthy), because the narrator Layth explicitly stated that he heard it from Tawus.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأدب / 12993