Contrary to the statement of those Iraqi scholars who say that it is not permissible for one performing an obligatory prayer to follow one performing a supererogatory (nafl) prayer.
Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) narrates that Sayyiduna Mu'adh (may Allah be pleased with him) used to perform prayer with the Messenger of Allah (peace and blessings be upon him), then would return and lead his people in prayer, and he would recite the same prayer for them.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب قيام المأمومين خلف الإمام وما فيه من السنن / 1633