Musannaf Ibn Abi Shayba 13:2273

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Al-A’mash narrated to us, from Talha, from Abd al-Rahman ibn Awsaja, from Al-Bara’ ibn Azib, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever gives a gift of silver, or a gift of milk, or guides someone to a path, it is for him like the freeing of a slave."