Hadith 545
Abu al-Nadr said: when the Iqamah was pronounced and the Messenger of Allah ﷺ saw that they (the people) were small in number, he would sit down, nd would not pray; but when he saw them (the people) large in number, he would pray.
Hadith 546
This tradition has been transmitted through a different chain of narrators in a similar way by Ali bin Abi Talib.