Amr bin Shu'aib narrates from his father, from his grandfather: The Prophet Muhammad (peace be upon him) said: "Command your children to pray when they are seven years old, and beat them for it (if they neglect it) when they are ten years old, and separate their beds. When a person marries off his slave or servant, he should not look at the area between the knees and the navel, because the part between the navel and the knees is 'awrah (private)."