Assalaamu alaykum. “Ibn ‘Abbaas narrated that ‘Umar went to the Prophet, sallallaahu 'alayhi wa sallam, and said, ‘Master I have been destroyed!’ The Prophet, sallallaahu 'alayhi wa sallam, asked ‘What thing has destroyed you?’ ‘Umar replied, ‘Last night, I turned my mount around (An expression which means he had sexual intercourse with his wife penetrating the vagina while mounting her from the rear).’ The Prophet, sallallaahu 'alayhi wa sallam, did not give a reply to ‘Umar, then Allaah, The Exalted, sent down this revelation: {Your wives are a place of sowing of seed for you, so come to your place of cultivation however you wish...}” As for the words ‘Kabool wa Dhabar’: what does that mean?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

It means that it is permissible for a man to have intercourse with his wife in any manner that he wishes provided that it be in her vagina; so he may have intercourse with her facing her or from behind her provided that he does not penetrate her from her anus but in her vagina only.

Ibn al-Atheer said, “He used the metaphor ‘mount’ in referring to his wife, meaning by this that he had sex with her in her vagina but from behind her, because the man usually positions himself on top of her (as if he is riding a mount) being face to face with her and when he gets on her from her back, so he used the metaphor (mount) for it.”

This is clear and there is no problem with it. What makes it even clearer is what Jaabir narrated; that the Jews used to say, “If one has sexual intercourse with his wife from her back, then she will deliver a squint-eyed child.” So this verse was revealed: {Your wives are a place of sowing of seed for you, so come to your place of cultivation however you wish and put forth [righteousness] for yourselves.} [Quran 2:223] [Al-Bukhari, Muslim, Ahmad, Abu Daawood, at-Tirmithi and Ibn Maajah]

Muslim narrated it with the following wording: “If he likes, he may (have intercourse) being on her back or in front of her, but it must all be through one opening (i.e. the vagina).”

Also, Umm Salamah said that the Prophet said about the verse in which Allaah says (what means): {Your wives are a place of sowing of seed for you, so come to your place of cultivation however you wish and put forth [righteousness] for yourselves.} that it means come to that single place (i.e. the vagina) however you wish.” [Ahmad and at-Tirmithi]

This is also clear if we look at the rest of the hadeeth that you mentioned and which was narrated by Ibn ‘Abbaas as it reads, “…but avoid the anus and menses.” [Ahmad and at-Tirmithi]

Allaah knows best.