Musannaf Ibn Abi Shayba 13:2181

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Sufyan narrated to us, from ‘Abd al-Rahman ibn Ziyad, he said: ‘Umar ibn ‘Abd al-‘Aziz wrote that one should return in the gift according to its value on the day it was gifted. And he wrote that the increase belongs to the recipient of the gift.