While we were with the Prophet. on a journey, one of the camels ran away. A man shot it with an
arrow and stopped it. The Prophet (ﷺ) said, "Of these camels some are as wild as wild beasts, so if one of
them runs away and you cannot catch it, then do like this (shoot it with an arrow)." I said, "O Allah's
Apostle! Sometimes when we are in battles or on a journey we want to slaughter (animals) but we
have no knives." He said, "Listen! If you slaughter the animal with anything that causes its blood to
flow out, and if Allah's Name is mentioned on slaughtering it, eat of it, provided that the slaughtering
instrument is not a tooth or a nail, as the tooth is a bone and the nail is the knife of Ethiopians."
Sahih al-Bukhari Book 72, Hadith 69
Ibn Umar misunderstood (the Quranic verse, "So come to your tilth however you will")--may Allah forgive him. The fact is that this clan of the Ansar, who were idolaters, lived in the company of the Jews who were the people of the Book. They (the Ansar) accepted their superiority over themselves in respect of knowledge, and they followed most of their actions. The people of the Book (i.e. the Jews) used to have intercourse with their women on one side alone (i.e. lying on their backs). This was the most concealing position for (the vagina of) the women. This clan of the Ansar adopted this practice from them. But this tribe of the Quraysh used to uncover their women completely, and seek pleasure with them from in front and behind and laying them on their backs.
When the muhajirun (the immigrants) came to Medina, a man married a woman of the Ansar. He began to do the same kind of action with her, but she disliked it, and said to him: We were approached on one side (i.e. lying on the back); do it so, otherwise keep away from me. This matter of theirs spread widely, and it reached the Messenger of Allah (ﷺ).
So Allah, the Exalted, sent down the Quranic verse: "Your wives are a tilth to you, so come to your tilth however you will," i.e. from in front, from behind or lying on the back. But this verse meant the place of the delivery of the child, i.e. the vagina.
Sunan Abi Dawud Book 12, Hadith 119