Is it permissible for a person praying alone to interrupt his prayer if another congregation is established in the mosque?

The Shaykh : And if he leaves that prayer and starts the prayer anew with the two who entered, there is no blame on him, because the reward for the first prayer has ended. The second congregation does not reach twenty-seven degrees, but there is no doubt that a man’s prayer with another man is better than his prayer alone.

The questioner : How should the student of knowledge

The Shaykh : see the row, this is before you, good.