What did the Jews claim about sexual intercourse from behind, and by which revelation was it proven to be wrong according to Prophet Muhammad (saw)?
 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)