What does one do if he prays the second prayer before the first when combining them?

Question : What does one do in this situation?

Answer : We say: Pray the one you prayed first, pray it now, the five. It becomes clear by example. A man was combining by delaying, then he entered the mosque and found the people praying the night prayer, so he joined them with the intention of the night prayer, and when he finished the night prayer, he prayed the sunset prayer. We say: The night prayer is not valid, why? Because he preceded it over the sunset prayer, and the order is a condition. So what does he do? He prays the night prayer. The sunset prayer is valid in its place, so he prays the night prayer, and both prayers become valid.