It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) that the Jews said to the Muslims: "Whoever has intercourse with his wife from behind, his child will be born cross-eyed." So Allah Almighty revealed this noble verse: «﴿نِسَاؤُكُمْ حَرْثٌ لَكُمْ ......﴾» [البقره: 222/2] meaning, "Your wives are your fields, so come to your field as you wish."