Musnad Ahmad 32:1741

Mu'ammal ibn Isma'il narrated to us, Hammad ibn Zayd narrated to us, from Ayyub and Hisham, from Muhammad—meaning Ibn Sirin—from Anas, who said: When the Messenger of Allah (peace and blessings of Allah be upon him) shaved his head in Mina, he took the right side of his head in his hand. When he finished, he handed it to me and said: "O Anas, take this to Umm Sulaym." When the people saw what he had singled her out for with that, they competed for the other side. This one took a piece, and that one took a piece. Muhammad said: "I narrated this to 'Ubaydah al-Salmani, and he said: 'That I should have a hair of it is more beloved to me than all the gold and silver that has come upon the face of the earth and within its belly.'"