Musannaf Ibn Abi Shaybah

Hazrat Aamir narrates that Hazrat Ibn Abbas (may Allah be pleased with them both) said: Hazrat Abbas said to me: O my son! I see that the Commander of the Faithful draws you close to himself, and seeks your counsel along with the companions of the Messenger of Allah (peace and blessings be upon him), and confides in you in private. So, on my behalf, remember three things: Beware that they do not test you with falsehood, never ever disclose their secrets, and never backbite anyone in their presence. The narrator says, I said to Hazrat Ibn Abbas (may Allah be pleased with them both): Each one of these is better than a thousand. He replied: Rather, it is better than ten thousand.