Musannaf Ibn Abi Shayba 13:1671

Abu Bakr narrated to us, he said: Shareek narrated to us, from ‘Amir ibn Shaqiq, from Abu Wa’il, who said: ‘Abdullah bought a slave girl for seven hundred dirhams, then her owner disappeared. He searched for him for a year, or he said: for a year. Then he went out to the mosque and began to give it away in charity, saying: "O Allah, it is for him; but if he refuses, then it is for me and upon me." Then he said: "Do like this with a found item or a stray animal."