Hadith.1201 - In the book of Ziyad ibn Marwan al-Qandi and in the Nawadir of Muhammad ibn Abi Umayr, it is narrated that Imam Jafar ibn Muhammad Al-Sadiq (as) said regarding a man who led a group in prayer from the time they left Khurasan until they reached Mecca, and then it was discovered that he was a Jew or a Christian
"They do not need to repeat their prayers”.