What is the ruling on an individual praying behind the row when there are vacant spaces?

The most preponderant view is that the prayer of a person praying alone behind a row is not permissible and invalid, and the prayer is nullified. He must repeat it due to the saying of the Messenger of Allah, may Allah's peace and blessings be upon him: "There is no prayer for one who prays alone behind the row." Some scholars have gone further to invalidate the prayer of one who prays alone behind the row absolutely. Prayer is not valid without forming rows, standing shoulder to shoulder, and filling gaps, as these are among the objectives of congregational prayer.