What do I do if I do not remember the last time that I have prayed certain prayers? For example, I am not quite sure when I last prayed the Thuhr.

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 ʻalayhi wa sallam, is His slave and Messenger.

If you doubt whether you performed the Thuhr prayer yesterday or not, or if you doubted whether you performed any other prayer or not, then scholars held different opinions in this regard. Some scholars held that you are obliged to perform the prayer that you doubt having prayed because the original state in this case is that you did not perform it, and your liability is not cleared from this obligation until you perform it. Other scholars maintained that you are not obliged to perform it based on mere doubts.

Based on the first scholarly view, if you doubt as to whether you missed one or two prayers, then you should choose the greater number and perform two prayers. Based on the second view, you are obliged to perform only the number of prayers of which you know with certainty that you missed them. Al-Furoo' reads, "If a person doubts performing a prayer and then knew the prayer for which he is liable with certainty, he is obliged to perform it to clear himself of his liability based on certainty. Abu Haneefah held that if a person doubts as to whether he performed the prayer or not and the time of the prayer expires, he is not obliged to perform it. Abu Al-Maʻaali stated that one's liability is not cleared except with certainty or predominant assumption."

It is more prudent to follow the first view. However, if the person who has these doubts suffers from obsessive whisperings (waswaas), then he should totally disregard these doubts, as ignoring them is the best remedy for them. For more benefit, please refer to fatwa 237529.

Allaah knows best.