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.
Doubt after performing any act of worship whether it is Wudhoo’ (ablution), Ghusl (shower taken in case of major impurity), prayer, and so on, is ineffective, no matter how long or short the period of time is. That is because acts of worship which are performed by those who are eligible for religious assignments are perfect in principle. Moreover, paying attention to doubt after that leads to undue difficulty and hardship, the two things that have no place in Islamic Sharee'ah. Allaah Almighty says (what means):
• {And (Allaah) has not placed upon you in the religion any difficulty.} [Quran 22: 78]
• {Allaah wills for you ease, and He does not will hardship for you.} [Quran 2: 185]
Allaah Knows best.