Musannaf Ibn Abi Shayba 9:113

'Abdullah ibn Idris narrated to us, from Mutarrif, from al-Hakam, who said: Shurayh said: "If a man marries off his son while he is young, it is binding upon him. Then, when he reaches puberty, if he divorces [her], then half of the dowry is upon the one who guaranteed it."