Al-Rabi' bin Subayh (may Allah have mercy on him) narrates from al-Hasan (al-Basri) (may Allah have mercy on him) that Ubaydullah bin Ziyad went to Sayyiduna Ma'qil bin Yasar (may Allah be pleased with him) while he was gravely ill. He said: Listen, I will tell you a hadith which I would not have told you were it not for the condition I am in. I heard the Messenger of Allah (peace and blessings be upon him) say: "Whomever Allah makes the guardian of a flock (of people) and he does not protect them with sincere goodwill, he will be among the people of Hell." He said: Could this hadith not have been told before this?
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17612