Sahih Bukhari, Chapter: Manumission of Slaves

Allah's Apostle (SAW) said, "Everyone of you is a guardian and is responsible for his charges. The ruler who has authority over people, is a guardian and is responsible for them, a man is a guardian of his family and is responsible for them; a woman is a guardian of her husband's house and children and is responsible for them; a slave ('Abu) is a guardian of his master's property and is responsible for it; so all of you are guardians and are responsible for your charges."