and pray in those very places.’ Mūsā added, ‘Nāfiʿ also told me that Ibn ʿUmar used to pray in those same spots.’ This is exactly the concession Imam Aḥmad—may Allah have mercy on him—allowed.
As for what he deemed blameworthy, Saʿīd ibn Manṣūr reports in his Sunan: Abū Muʿāwiyah narrated to us, al-Aʿmash narrated from Maʿrūr ibn Suwayd, from ʿUmar—may Allah be pleased with him—who said, ‘We set out with him on a pilgrimage he performed, and at the dawn prayer he recited:
“Have you not seen how your Lord dealt with the Companions of the Elephant?” (Sūrat al-Fīl 105:1)
and—in the second rakʿah—
“For the security of Quraysh.” (Sūrat Quraysh 106:1)
When he returned from that ḥajj he saw the people rushing toward a mosque and asked, “What is this?” They replied, “A mosque in which the Messenger of Allah ﷺ prayed.” He said, “This is exactly how the People of the Book before you were ruined: they turned the traces of their prophets into places of worship. Whoever of you finds the prayer time upon him there, let him pray; whoever does not, let him continue on his way.”’
ʿUmar—may Allah be pleased with him—thus disliked turning the Prophet’s place of prayer into a recurring gathering, and he clarified that the People of the Book were destroyed by precisely such behavior.
In another narration he saw people heading off in different directions and asked, “Where are these people going?” He was told, “Commander of the Believers, they are going to a mosque in which the Messenger of Allah ﷺ once prayed, and they wish to pray there.” He said, “Those before you perished for this very reason: they pursued the footprints of their prophets and turned them into churches and synagogues. If the time for prayer overtakes any of you in one of these mosques, let him pray…"