Sayyiduna Amr bin Shu'aib narrates from his father, and he from his grandfather (Sayyiduna Abdullah bin Amr bin al-As) (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: When your children reach the age of seven, start instructing them to perform prayer, and when they reach the age of ten, discipline them (if they are negligent in prayer), and separate their beds. And when a man marries his slave-girl to his slave or his laborer, he should not look at her (private) parts; (remember that) the limit of 'awrah is from the navel to the knees.