If a person comes to join two people in prayer, does the imam move forward or does the ma'mum move back?

Question:
May Allah reward you. Honorable Shaykh, this questioner says: If a person comes to two people who are praying, and he wants to... Yes. He says: May Allah keep you safe. If a person comes to two people who are praying and he wants to pray with them, does the imam move forward and then line up with the ma'mum, or does he say the takbir next to the ma'mum, or does he move forward, or does he and the ma'mum move back?

Answer:
It is all permissible for them. They may move back from the imam, and they may move the imam forward and line up in his place. It is all permissible, if Allah wills. Yes.