Sahih Muslim Book 31, Hadith Number 5959.
Chapter : Merits of Zaid b. Harith and Usama b. Zaid (Allah be pleased with them).
Salim reported on the authority of his father that Allah’s Messenger (may peace be upon him) said on the pulpit: You object to the command of Usima b. Zaid as you had objected before to the command of his father (Zaid). By Allah, he was most competent for it and, by Allah, he was dearest to me amongst people and, by Allah, the same is the case with Usama b. Zaid. He is most dear to me after him and I advise you to treat him well for he is pious amongst you.