Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh))
Bukhari :: Book 6 :: Volume 60 :: Hadith 51
Narrated Jabir:
Jews used to say: "If one has sexual intercourse with his wife from the back, then she will deliver a squint-eyed child." So this Verse was revealed:--
"Your wives are a tilth unto you; so go to your tilth when or how you will." (2.223)