It is narrated from Hazrat Amr bin Abasah (may Allah be pleased with him) that the Holy Prophet (peace and blessings of Allah be upon him) said: The two worst tribes among the Arabs are Najran and Banu Taghlib.
Hadith Referenceمسند احمد / تتمہ مُسْنَدِ الْكُوفِيِّينَ / 19442