Sunan Abi Dawud Book 2, Hadith 104
The Prophet (ﷺ) said: Command a boy to pray when he reaches the age of seven years. When he becomes ten years old, then beat him for prayer.
The Messenger of Allah (May peace be upon him) was asked about saying prayer at places where the camels kneel down. He replied; Do not say prayer at places where the camels kneel down because they are the places of devils. And he was asked about saying prayer in the fold of sheep. He replied: pray there because they are the places of blessing.
The Messenger of Allah (ﷺ) said: Command your children to pray when they become seven years old, and beat them for it (prayer) when they become ten years old; and arrange their beds (to sleep) separately.