Musannaf Ibn Abi Shayba 33:500

Yazid narrated to us, he said: Hariz ibn Uthman informed us, he said: Habban ibn Zayd al-Shar'abi narrated to me, and he was a friend of al-Nu'man, and al-Nu'man had appointed him over the arrows. He said: He heard al-Nu'man saying, "Beware, indeed the workers of Allah are guaranteed by Allah; beware, indeed the workers of the children of Adam do not possess their own guarantee." He said: So when al-Nu'man descended from his pulpit, he came to him and asked to be relieved of his duty. He said, "What is the matter with you?" He said, "I heard you say such and such."