Musannaf Ibn Abi Shayba 9:115

Waki’ narrated to us, from Shu’bah, who said: I asked al-Hakam and Hammad about a man who marries off his son while he is young. Al-Hakam said: It is upon the son. Hammad said: It is upon the father. Qatadah said: Ibn Umar said: It is upon the one whom you married him to, meaning the dowry is upon the son.