Sahih Muslim Book 8, Hadith Number 3363.

Chapter: Permissibility of having sexual intercourse with one’s wife from the front or from behind avoiding the anus.

Jabir (Allah be pleased with him) declared that the Jews used to say: When a man has intercourse with his wife through the vagina but being on her back, the child will have squint, so the verse came down: “Your wives are your tilth; go then unto your tilth as you may desire”(ii. 223)