Jabir (b. Abdullah) (Allah be pleased with him) reported that the Jews used to say that when one comes to one's wife through the vagina, but being on her back, and she becomes pregnant, the child has a squint. So the verse came down:

" Your wives are your ti'Ith; go then unto your tilth, as you may desire."

وَحَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَخْبَرَنَا اللَّيْثُ، عَنِ ابْنِ الْهَادِ، عَنْ أَبِي حَازِمٍ، عَنْ مُحَمَّدِ، بْنِ الْمُنْكَدِرِ عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، أَنَّ يَهُودَ، كَانَتْ تَقُولُ إِذَا أُتِيَتِ الْمَرْأَةُ مِنْ دُبُرِهَا فِي قُبُلِهَا ثُمَّ حَمَلَتْ كَانَ وَلَدُهَا أَحْوَلَ ‏.‏ قَالَ فَأُنْزِلَتْ ‏{‏ نِسَاؤُكُمْ حَرْثٌ لَكُمْ فَأْتُوا حَرْثَكُمْ أَنَّى شِئْتُمْ‏}‏