they are the quarters and the suburban districts: one says, “the quarter of the Banū ʿAbd al-Ashhal” or “the quarter of the Banū al-Najjār,” meaning the neighborhood allotted to each clan.

Al-Baghawī states in Sharḥ al-Sunnah:
“The intended meaning is the localities that contain the dwellings. Among the proofs for this is the Divine saying, ‘I will show you the abode of the rebellious’ (Qur’an 7:145), for they used to call the settlement in which an entire tribe resided a dār. Likewise the ḥadith, ‘There was no house left but a mosque was built in it.’”
This was cited by al-Shawkānī.

Shaykh ʿAlī al-Qārī, in his commentary on the Mishkāt, writes:
“al-dūr—the plural of dār—is a comprehensive term for a building, a yard, or a neighborhood. What is meant here are the quarters, for the Arabs would call the quarter in which a tribe was gathered a dār; or it may be understood as designating a room within the house set aside for prayer, like a mosque in which the members of the household pray, as Ibn al-Malik suggested. The first interpretation, however, is the sound one, and upon it the practice is based.”

I later found that Ibn Ḥajar also maintained that what is meant here are the quarters and tribal districts. The wisdom in the Prophet’s instruction that each district build its own mosque is that the people of one neighborhood may find it impossible or too difficult to walk to another, thereby missing the reward of the mosque and the virtue of performing congregational prayer in it. They were therefore ordered to build so that each quarter could worship in its own mosque without hardship.

Al-Baghawī adds: ʿAṭāʾ said, “When Allah opened the cities to ʿUmar (may Allah be pleased with him), he ordered the Muslims to build mosques and told them not to erect two mosques such that one would compete with or harm the other. One form of such harm is splitting the congregation when there is already a mosque spacious enough for them; if it becomes too small, its enlargement is recommended, or a mosque that will accommodate them should be built.”

After quoting the forthcoming hadith of Ibn ʿAbbās in the wording, “I have not been commanded to adorn mosques with elaborate construction,” Ibn Ḥazm said: