The ruling on one who enters the mosque and finds no space in the row

This is a letter we received from our brother Muqtad al-'Anizi from al-Kharj, in which he says: If I enter the mosque and the congregation of worshippers has completed the rows and there is no space in the row, what should I do? Should I pull a person from the previous row to stand beside me, or should I pray alone? It often happens that the imam finishes the prayer and no one else comes to pray with me. Please advise us, may Allah reward you.
Answer: It is obligatory for one who enters while the imam is in prayer to look for a space and enter it, or to look for the ends of the rows so that he stands in a row with the people. As for pulling someone else, that is not permissible. The hadith reported regarding this: is a weak hadith that does not serve as proof. Also, pulling a man from the row opens up a space, and the Messenger of Allah (peace and blessings be upon him) commanded filling the gaps and closing the spaces. However, he should wait until he finds a place in the row or until some people come and he stands in a row with them. As for standing alone, that is not permissible; because the Messenger (peace be upon him) said: And when he saw a man praying behind the rows alone, he ordered him to repeat the prayer.
But if it is possible for him to stand in a row with the imam on his right, there is no harm. The summary is that if he does not find a place, he should wait, even if he misses the prayer. When the imam finishes the prayer, he prays alone. If someone comes and prays with him, praise be to Allah. If he finds a space in the first row or the second row or at the ends of the rows, he stands in a row with the people. If he is able to enter until he stands with the imam on his right, he does that. This is what is prescribed and this is what is obligatory.
The presenter: May Allah reward you.