Imaam laughs in salaat

Question: If a masbooq joins the salaat after the Imaam makes the final tashahhud, and the Imaam laughs in his salaat, what will be the state of the masbooqs salaat?

Answer: The salaat of the masbooq (one joins the Imaam after the ruku’) will become baatil (nullified) in this instance. He will have to re-commence his salaat.