It is narrated about Sayyiduna Abu al-Darda' (may Allah be pleased with him) that he heard a man reviling another man in a loud voice, so he said: I heard the Prophet (peace and blessings be upon him) say: "Foul speech is blameworthy, and being a bad master is blameworthy."
Al-Tabarani recorded it. Its chain contains Abdullah bin Aradah, whom Abu Dawud declared thiqah (trustworthy), and Yahya bin Ma'in called him da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأدب / 13008