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)
The main values taught through this hadith are freedom, caution, and trustworthiness. We should have faith in Allah's words but also use our intellect to verify facts before believing them blindly. We should also respect each other's freedom within marriage and not impose any restrictions on them based on baseless beliefs or superstitions.