Al-Hasan al-Basri (may Allah have mercy on him) relates: Ubaydullah bin Ziyad came to visit Sayyiduna Ma'qil bin Yasar (may Allah be pleased with him) while we were with him, and Ma'qil (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Any man whom Allah makes the guardian of a flock (of people) and he dies while being treacherous towards them, Allah Almighty forbids Paradise to him."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17590