The Ruling on a Person Praying a Voluntary Prayer Leading One Who Is Praying an Obligatory Prayer

The presenter: This is a message from the sender Salim Muhammad al-Zahrani, who says in his message: Peace be upon you, and Allah’s mercy and blessings, and to the honorable Shaykhs who give of their time in the path of guiding citizens and answering their inquiries, and to His Eminence Shaykh Abd al-Aziz ibn Baz, I hope for an answer to these questions:
If a man enters while I am praying a voluntary prayer, and that man believes that I am praying an obligatory prayer, so he takes me as his imam to pray the obligatory prayer with me, what is the ruling in this case? Do I have to push him away before starting with him? I have been told that one must distinguish between the obligatory and the voluntary prayer by raising one’s voice in the takbirs for the obligatory prayer, unlike the voluntary prayer. What is your Eminence’s opinion on this?
Answer: The Sunnah of the Messenger of Allah (peace and blessings be upon him) indicates that there is no harm in the ma’mum (one praying behind the imam) being obligated to pray while the imam is praying a voluntary prayer. So if you, O questioner, are praying a voluntary prayer and a man comes and stands behind you to pray his obligatory prayer, there is no harm and no blame according to the correct view. Although some scholars hold that one praying a voluntary prayer should not lead one who is obligated to pray, that is a weak opinion, a weaker position in terms of evidence. The correct view is that there is no harm in it. So if he joins you, there is no harm in you leading him while he prays an obligatory prayer and you pray a voluntary prayer; there is no harm in that. And there is no basis for what you mentioned, namely that one raises his voice in the takbir of the obligatory prayer and lowers it in the voluntary prayer. I do not know of any basis for this. Rather, the takbir is the same in both; one says takbir in his obligatory prayer and his voluntary prayer alike. We do not know of anything in this matter, except for the imam, who says takbir and raises his voice because he alerts the people and informs them. As for the ma’mum who is praying alone, his voice in the obligatory prayer or the voluntary prayer is the same. We do not know of any Sunnah that distinguishes between them. Yes.