al-Suyūṭī, as cited by al-Manāwī, said:

“Some people failed to notice that having a miḥrāb (prayer-niche) inside a mosque is an innovation. They imagined it had existed in the Prophet’s time, whereas it was not found in his day, nor in the time of any of his caliphs; it only appeared in the second century, despite the established prohibition against adopting it.”

He then critiques the well-known statement of al-Zarkashī: “Putting up a miḥrāb is permissible, not disliked; people have always done so without objection,” responding:

“There is no authoritative transmission within the school for that view, while a prohibition has been authentically established.”

The prohibition he has in mind appears to be the report recorded by al-Bayhaqī through the chain of transmission: ʿAbd al-Raḥmān ibn Mughrāʾ – Ibn Abjar – Naʿīm ibn Abī Hind – Sālim ibn Abī al-Jaʿd – ʿAbd Allāh ibn ʿAmr, who said that the Messenger of Allah ﷺ declared:

“Beware of these slaughter-places,”—meaning the miḥrābs.

This isnād is sound (ḥasan): all its transmitters are trustworthy and belong to Muslim’s circle of narrators, with the sole exception of ʿAbd al-Raḥmān ibn Mughrāʾ. The criticism leveled at him concerns only his narrations from al-Aʿmash, and, as you can see, this report is not among them. Al-Dhahabī says of him in al-Mīzān:

“There is nothing wrong with him, if Allah wills. Al-Kadīmī related that he heard ʿAlī say: ‘He is not one of those we left out; he was nothing of the sort.’”

Ibn ʿAdī follows this by saying:

“What ʿAlī said is exactly so. The only objection to Abū Zuhayr—ʿAbd al-Raḥmān’s kunya—concerns ḥadīths he reports from al-Aʿmash that the reliable transmitters do not corroborate.”

Abū Zurʿah also said: “He is truthful.”