What is the ruling on my prayer if I accidentally touched my penis after performing ablution (Wudu'), then forgot and prayed?

Touching the private parts (penis) invalidates ablution (wudu') according to the most preponderant opinion among scholars, whether the touching was intentional or unintentional. This is the more cautious approach and clears one's conscience, due to the generality of the narrations concerning invalidation. One must repeat the prayer that was performed after touching the private parts, because it was a prayer without purification.