Musannaf Ibn Abi Shayba 9:771

Waki’ narrated to us, from ‘Ali ibn ‘Ali, who said: I heard al-Hasan saying: The polytheists would not cease to be harsh toward the Muslims, and they would say: "It is not permissible for you to approach women except from one way." So Allah, the Exalted, revealed: "So come to your cultivation however you wish."