He prayed a long time thinking that touching his sexual organ does not invalidate Wudhoo’
14-1-2014 | IslamWeb
Question:
Years ago I read a book of Fiqh indicating that a man touching his penis does not invalidate Wudhoo’ (i.e. ablution). I acted according to this opinion for many years. Then I read a Fatwa signifying that it is only the opinion of Hanafi scholars and is a weak opinion and that the opinion of the majority of scholars is that such an action invalidates Wudhoo’. What is the Sharee‘ah ruling on my past prayers? I certainly touched my penis during this period but it is impossible to know how many times. Am I required to make up for the past prayers? If so, how should I do this?
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
The majority of scholars are of the opinion that touching one's sexual organ with his hand invalidates Wudhoo’. Busrah 
narrated that the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said: "Whoever touches his sexual organ must perform Wudhoo’."
Hanafi scholars are of the opinion that touching one's sexual organ does not invalidate Wudhoo’. However, the opinion of the majority of scholars is supported with a stronger proof and it is more cautious.
In conclusion, we advise the questioner to adopt the opinion of the majority of scholars in the future. As for the past prayers, you are not required to make them up since you were following the other opinion.