Narrated Ibn 'Abbas:
'Umar came to the Messenger of Allah (ﷺ) and said: 'O Messenger of Allah! I am ruined!' He said: 'Why are you ruined?' He said: 'I turned my mount during the night (meaning that he went into his wife from behind).' He said: So the Messenger of Allah (ﷺ) did not say anything in reply to him. Then Allah revealed this Ayah to the Messenger of Allah (ﷺ): 'Your wives are a tilth for you, so go to your tilth when or how you will (2:223).' From the front, the back, avoiding the anus, and menstruation.