Hazrat Jabir says that I asked Hazrat Abu Ja'far, Hazrat Salim, Hazrat Qasim, and Hazrat Ata about a person who joins a congregation thinking it is the Zuhr prayer, but they are actually performing the Asr prayer. They replied that after completing the prayer with salam, he should perform the Zuhr prayer; however, his Asr prayer will be valid. He says that I asked Hazrat Amir and Hazrat Muslim bin Subaih about this, and they replied that after finishing, he should first perform the Zuhr prayer and then the Asr prayer, because Allah the Exalted has made Zuhr obligatory before Asr. Therefore, the Zuhr prayer cannot be performed after Asr. Hazrat Jabir states that this is also the opinion of Hazrat Hammad and Ibrahim.