Chapter: It is impermissible to slaughter for Allah at a place where animals are slaughtered for anyone other than Allah.

And the words of Allah, Most High:
“Never stand in it. A mosque founded upon piety from the very first day is worthier that you should stand therein. In it are men who love to purify themselves, and Allah loves those who purify themselves.” [Al-Tawbah: 108]

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Relevance of this chapter to the Book of Tawḥīd: it follows directly after the previous chapter. The preceding chapter explained the ruling on offering sacrifice to other than Allah, while the present one blocks the means that lead to that practice and forbids resembling its people.

“where animals are slaughtered for other than Allah”: i.e., a place that has been prepared and intended specifically for that purpose.

“Do not stand in it”: that is, do not pray in the Mosque of Harm (Masjid al-Dirār).

“a mosque founded”: built.

“upon piety”: upon obedience to Allah and His Messenger.

“those who purify themselves”: those who cleanse themselves from both tangible and intangible impurities.

Overall meaning of the verse: Allah, exalted is He, forbids His Messenger ﷺ to pray in the Mosque of Harm, which the hypocrites built in opposition to the Qubāʾ Mosque and out of disbelief in Allah and His Messenger. They asked the Prophet ﷺ to pray in it so they could use his prayer as proof to justify their deed and hide their falsehood. The Prophet ﷺ promised to do so, unaware of their evil intent. Allah therefore prohibited him from doing that and urged him instead to pray in the Qubāʾ Mosque, which was built upon obedience to Allah and His Messenger, or in his ﷺ own mosque on—