He asks how to combine this with the regular sunnah prayers, which are twelve rak'ahs.

This hadith is the hadith of Umm Habiba, and the chain of narration in that hadith is weak, because it was narrated from Anbasa from Umm Habiba, and some have criticized it due to Anbasa not having heard from her.

We say regarding this that this hadith is not established concerning the four units after Dhuhr, but the four units before it are established.

The four units before it are established in the authentic narration from Aisha, as it came in the narration of Ibn al-Muntashir from his father from Aisha, that she said: The Prophet ﷺ never left four units before Dhuhr.

And two units before Fajr, and likewise it also came in the narration of Abdullah ibn Shaqiq from Aisha, may Allah be pleased with her.

And in the authentic narration, the Prophet ﷺ used to pray four units before Dhuhr in his house, then he would go out and lead the people in prayer, then return and pray two units in his house.

As for the four units after Dhuhr, there is no authentic hadith from the Messenger of Allah ﷺ about them, and what is established is the four before.

As for the narration that whoever prays twelve units for Allah in a day and night, Allah will build a house for him in Jannah, it is divided differently, and the issue arises regarding that.

In the case of this hadith being established, and the correct view is that it is not established, and Allah knows best.