Musannaf Ibn Abi Shayba 13:817

Abu Bakr narrated to us, he said: Shareek narrated to us, from ‘Amir, from Shaqiq, from Abu Wa’il, who said: ‘Abdullah bought a slave girl for seven hundred dirhams, and her owner was absent. He made her known for a year, or he said: for a cycle. Then he went out to the mosque and began to give charity, saying: "O Allah, it is for him [the owner]; but if he refuses, then it is for me and upon me." Then he said: "Thus do with a found item or a stray animal."