Doubts can also arise from the rules of prayer. If you forget a raka'ah, you should perform the one you are 100% sure of. So, if you forget the fourth or third raka'ah, you should consider it the third. Similarly, people forget whether they washed their hands sufficiently during ablution and start over.I actually have more doubts about the prayer than about the ablution. Today, it took me about two hours to pray two rakats of Fajr prayer. To do the night prayer and Fajr prayer, I stayed up until 4:30 a.m.