I say: Set against these narrations are other reports from ʿUmar, al-Shaʿbī, and Ibrāhīm—recorded by Ibn Abī Shaybah 2/223 and by ʿAbd al-Razzāq 3/81–82—which state that a person may not do so when a road or the like lies between him and the imam. Most likely, therefore, the first set of narrations is to be understood as referring to a case of necessity, such as the mosque being full, just as Hishām ibn ʿUrwah said:

“On one occasion my father and I came and found the mosque filled to capacity, so we followed the imam in prayer from a house next to the mosque, a road lying between the two.”

ʿAbd al-Razzāq 3/82 transmits this with a sound chain from him.

It is no secret to the jurist that an unqualified ruling of permissibility conflicts with the hadiths that command the rows to be closed and the gaps to be filled; these must be observed and acted upon except when a valid excuse exists. For that reason Shaykh al-Islām [Ibn Taymiyyah] said in Majmūʿ al-Fatāwā 23/410:

“No one should form rows in alleyways or shopfronts while the mosque still has free space, and whoever does so deserves disciplinary action. Anyone who comes later may step over him and enter to complete the forward rows, for such a person enjoys no inviolability. When the mosque is filled with rows, however, they may form rows outside it, and once the rows are thus connected in the streets and marketplaces their prayer is valid. But if they form rows with a roadway between them and the next row along which people walk, their prayer is invalid according to the soundest of the two scholarly opinions.

Likewise, if there is a wall between them and the rows so that they cannot see those rows, and they merely hear the takbīr (the declaration ‘Allāhu akbar’) without any need, their prayer is, according to the stronger view, invalid. The same applies to anyone who prays in his shop while the street is empty: his prayer is invalid. He is not entitled to remain in the shop waiting for the rows to reach him; rather, he must go to the mosque and fill the first row, then the next, and then the next.”