ANSWER:

The prayer is valid but he is sinful. 

If one has the strong urge to pee but he prays first and while praying he has a strong urge to pee but he prays and uses the bathroom later even though he knew he had to pray from way before but he wanted to keep wudu and purposely held his pee so that his wudu wouldn’t break should he pray again or is the salah valid?

Prayer |