Ruling on joining the prayer of a person praying alone

Question:
If a person enters the state of ihram for one of the obligatory prayers in the mosque or elsewhere, praying alone, and then another person or more come and line up with him, is that valid?

Answer:
The correct view is that it is valid. If it is one person, he lines up to his right. If more than one person is present, they line up behind him and make him the imam. There is no blame in this according to the most correct opinion of the scholars, because the Messenger of Allah (peace and blessings be upon him) used to pray at night alone, and then Ibn Abbas came and lined up to his left, so he moved him to his right and prayed with him, and the Prophet (peace and blessings be upon him) did not intend to lead the prayer when he entered the state of ihram.
It is also authentic from him (peace and blessings be upon him) that on one of his journeys, he was praying alone, and two of the Companions came and lined up to his right and left, so he placed them behind him and prayed with them. If this is permissible in a voluntary prayer, it is permissible in an obligatory prayer, because they are the same in rulings except for what is specified by evidence. Also, if it were not permissible in an obligatory prayer, the Prophet (peace and blessings be upon him) would have alerted them and informed them that such a thing is only permissible in a voluntary prayer, not in an obligatory one. Since he did not inform them of that, it indicates that the ruling is the same. And success is from Allah.