Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Abu Ishaq that he says Hazrat Ali (may Allah be pleased with him) said: There are a few things that if you drive your mounts, you will destroy and perish your mounts before attaining the like of these things. A servant should not place hope in anyone except his Lord. A servant should fear only his own sins. A person who does not know should not feel shy of learning, and when a person is asked about something unknown to him, he should not feel shy to say "Allah knows best." And know this: the place of patience in faith is like the place of the head in the body. So when the head is gone, the body is gone, and when patience is gone, faith is gone.