Question:

Very often when I stand up to pray, I experience doubts in my mind as to whether my purification or Wudhu is nullified or not. What should I do in such a situation: Should I leave the Salah and purify myself and then resume my Salah, or should I simply continue in my Salah and not bother about such doubts?

Answer:

The answer to your question may vary according to one of the two scenarios described below:

If you are suffering from incontinence, or bladder control problems, then you should do the following:

You should make sure to wash yourself and perform your ablution close to the time of the Salah you intend to perform. After having done so, if, during the course of your Salah, you were to experience any wetness, drops, etc., you need not worry about it; it shall be shall be considered as “excused” in your case. Allah clearly tells us
“He has not appointed any hardship for you in your religion.” (Q. 22:78) But we must, once again, stress that in this case, one must only perform the necessary purification and Wudhu as close to the Salah as possible.

Regarding the second scenario:
If you do not suffer from incontinence or bladder problems, then you must ask yourself whether you are certain that you have started your Salah after having clearly established the necessary purification and Wudhu or not. If you are definitely certain that you have done so, then you don’t need to pay attention to such intrusive thoughts or doubts that assail your mind unless you see some tangible signs indicating otherwise. Such tangible signs include wetness, foul smell or sound of passing winds or fart, etc. If you were to experience any of these tangible signs, you must break your Salah and resume it only after having performed the requisite procedure of purification and Wudhu,

If, on the other hand, you did not experience any such tangible signs indicated above, then you don’t need to pay any attention to such doubts. This is in accordance with the principle of Fiqh that “Certainty cannot be undermined by mere doubt or hesitation”. Therefore, you should continue your Salah until such time that you see clear signs to the contrary.

In this case indicated above, it important for us to know that such nagging doubts are due to the whisperings of Satan as the Prophet (peace be upon him) told us that Satan will approach us in our Salah, trying to distract us from it. In doing so, he will definitely play different cards with different people. If, in your case, he is to trying to cast doubts in your mind regarding your purification, in the case of another, it may be by suggesting some other thoughts, and, hence, the remedy for it is simply turning to Allah for protection and invoking His help against the accursed one.

Source: Islam.ca