Sunan Abi Dawud Book 42, Hadith 70
The tradition mentioned above has also been transmitted by Dubai’ah b. Husain al-Tha’labi through a different chain of narrators to the same effect.
We entered upon Hudhaifah. He said: I know a man whom the trails will not harm. We came out and found that a tent was pitched. We entered and found in it Muhammad b. Maslamah. We asked him about it. He said : I do not intent that any place of your towns should occupy me until that which is prevailing is removed.
I said to ‘All (Allah be pleased with him) : Tell me about this march of yours. Is this an order that the Messenger of Allah (May peace be upon him) had given you, or is this your opinion that you have? He said: The Messenger of Allah (May peace be upon him) did not give me any order; but this is an opinion that I have.