Those who permit this without restriction cite the well-known hadith of Mu‘ādh:

“He used to pray behind the Prophet, may Allah bless him and grant him peace, then go and lead his people in prayer.”

One version states:

“The first prayer was obligatory for him, and the second was voluntary.”

Those who prohibit this have no sound proof. They cite wording that does not address the point in dispute, such as his saying:

“The imam has only been appointed to be followed, so do not differ from him.”

They also cite the statement that “the imam is a guarantor,” arguing that his prayer cannot be of a lesser status than that of the follower. Neither statement refutes the evidence cited above. The difference intended here concerns actions, as the explanatory wording makes clear. Otherwise, a follower may repeat the prayer, thereby offering a voluntary prayer behind someone offering an obligatory prayer, as is the position of the overwhelming majority of scholars.

This is supported by his statement in the authentic hadith:

“After me there will be rulers who delay the prayer beyond its prescribed time. Pray at its prescribed time, then let your prayer with them be voluntary.”

Furthermore:

“He prayed at al-Khayf Mosque and saw two men who had not prayed. He asked, ‘What prevented you from praying with us?’ They replied, ‘We have already prayed at our lodgings.’ He said, ‘If you have prayed at your lodgings and then come to a mosque where a congregation is praying, pray with them, for it will be a voluntary prayer for you.’”

The Sunan collections also relate:

“He saw a man praying alone and said, ‘Will someone not give this man charity by praying with him?’”

Thus, several hadiths establish that someone offering a voluntary prayer may pray behind someone offering an obligatory prayer. The reverse has also been established. It is therefore clear that matching the imam’s intention regarding whether the prayer is obligatory or