Praise be to Allah.
Shaykh Muhammad Ulays (may Allah have mercy on him) said:
One of the obligatory parts of ghusl is rubbing, i.e., passing the hand or something else over the part of the body that is being washed…
In general, it is sufficient to think it is most likely that he has done that, according to the correct view. It is sufficient in order for him to be regarded as having done what is necessary, according to consensus; however, it is not stipulated that he should think it most likely that he has done that, in the case of one who is overwhelmed with uncertainty, because he is unable to reach that level of certainty. In his case, it is sufficient for him to have some doubt. He must pay no attention to it, and there is no remedy for him except that.
End quote from Minah al-Jaleel (1/127).
The guideline with regard to what constitutes overwhelming uncertainty is that this uncertainty affects him constantly every day and never stops.
Al-Hattaab said in Mawaahib al-Jaleel (1/466):
The one who is overwhelmed with uncertainty is the one who is uncertain about every wudoo’ or every prayer, or that happens to him once or twice a day. If it only happens to him every two or three days, then he is not overwhelmed with uncertainty. End quote.
The point is that what is meant by the phrase in Minah al-Jaleel is that in order to regard rubbing as having taken place, it is sufficient for him to think it was most likely that he has passed his hand over the part that was to be rubbed; that is sufficient.
This applies in the case of one who is not overwhelmed by uncertainty.
As for the one who is overwhelmed by uncertainty, he is not required to think it most likely that he has passed his hand over that part in order for his wudoo’ to be valid; rather it is sufficient for him just to think that it happened, even if he does not think it is most likely. Then his wudoo’ will be valid.
Suffering from a great deal of uncertainty means that he is excused from having to be certain, because telling him that he must be certain will cause him a great deal of difficulty, and Islam came to make things easy and remove hardship.
Allah, may He be exalted, says (interpretation of the meaning): “Allah intends for you ease and does not intend for you hardship” [al-Baqarah 2:185] and “Allah does not intend to make difficulty for you” [al-Maa’idah 5:6].
Moreover, the remedy for a great deal of uncertainty is not pay any attention to it, because if the one who is affected by waswaas [whispers from the Shaytaan; intrusive thoughts] pays attention to every uncertainty, it will make the matter worse and he will become controlled by his waswasah.
Ad-Dardeer said in ash-Sharh as-Sagheer (1/170): If someone who is not overwhelmed with uncertainty is unsure as to whether water reached part of his body, he must wash it by pouring water on it and rubbing it. As for the one who is overwhelmed with uncertainty – who is the one who can never be certain about anything – what he must do is ignore it, because succumbing to waswaas will undermine one’s faith altogether. We seek refuge with Allah from that.
As-Saawi said in his commentary: The words “if he is unsure” mean that he must wash every part of the body with certainty, and it is sufficient for him to think that that is most likely to be the case, according to the correct view – for one who is not overwhelmed with uncertainty.
The words “he must” mean that he cannot be absolved of this obligation unless he is certain or thinks it most likely.
Al-‘Adawi said regarding the one who is overwhelmed with uncertainty and what is required of him:
It is sufficient for him to think that that is the case; he does not have to be certain or think it most likely, and he does not have to repeat it.
End quote from Kifaayat at-Taalib ar-Rabbaani (1/216).
The one who is overwhelmed with uncertainty should pay no attention to his doubts, and in his case it is not stipulated that he think it be most likely; rather he may base his actions on uncertainty, and that is sufficient for him. This was stated by our shaykh.
End quote from Haashiyat ad-Dasooqi ‘ala ash-Sharh al-Kabeer (1/135).
It was said that the one who is overwhelmed with uncertainty may base his actions on the first thought that comes to his mind, and he may ignore whatever thoughts come after that.
It says in at-Tawdeeh Sharh Mukhtasar Ibn al-Haajib (1/163):
With regard to the one who is overwhelmed with uncertainty, what counts is the first thought that crosses his mind, according to consensus.
What he mentioned about the first thought being the one that counts is the view of some of the Qayrawaanis (from Kairouan), and was also followed by some of the later scholars who said: That is because the first thought came when his mind was clear, and what comes after that are irrational thoughts.
Ibn ‘Abd as-Salaam said: The apparent meaning of what it says in al-Mudawwanah and elsewhere is that he does not have to repeat his action, regardless of what crossed his mind. This is what some of those whom we met thought most likely to be correct and stated. He mentions that he discussed this issue with the Easterners, and he explained that in the case of the one who is overwhelmed with uncertainty – and anyone else who meets this description – the first thought that comes to his mind and what comes after it is not something that could be reliable. And real-life situations testify to this fact. End quote.
See also: at-Taaj wa’l-Ikleel (1/301) and at-Taaj wa’l-Ikleel (2/19).
And Allah knows best.