I was with one of the young men, and when the imam finished the prayer and I stood up to complete my prayer since we were late, I heard him say that this imam prayed two rak'ahs, and the brother did nothing but continue the prayer following the imam after the conversation and interruption, and he did not renew the Takbir al-Ihram especially since he spoke saying: this sheikh prayed two rak'ahs, and he completed with the imam. What is the ruling on his prayer?