The World Federation One Stop Fiqh

Ruling 1363

With regard to someone who has to make up, for example, a number of ṣubḥ or ẓuhr prayers, but he does not know how many or has forgotten how many – for example, he does not know if it is three, four, or five prayers that he has to make up – then, in the event that he performs the lower number, it is sufficient. However, it is better that he perform prayers up to the extent that he can be certain of having performed all of them. For example, if he has forgotten how many ṣubḥ prayers have become qaḍāʾ but he is certain that it is not more than ten, then as a recommended precaution he should perform ten ṣubḥ prayers.