Musannaf Ibn Abi Shaybah

Hazrat Ata says that if a person comes to the mosque for prayer and the row is complete, then if he has the ability to join the row, he should do so. If this is not possible, he should take hold of a person and make him stand with himself. He should not stand alone.

Hazrat Amr bin Maymoon says that if I come for prayer and the row has been completed, what should I do? He replied that make one person stand with you. If you pray alone, then repeat the prayer.