If a person finds something on his body after wudu that could have prevented water from reaching his skin, but he does not know if it occured after wudu or before it, what should he do?

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 ‘alayhi wa sallam, is His slave and Messenger.

Ablution is not valid if there is an obstacle which prevents the water from reaching the skin of a limb that must be washed during ablution, unless the obstacle is very small, as this is not a problem according to some jurists like Ibn Taymiyyah .

Whoever sees an obstacle after having performed ablution and does not know whether this occurred before ablution or after it, then if he had not yet performed the prayer with that ablution, it is better for him to remove the obstacle and perform ablution again. However, if he had already performed the prayer with that ablution, then he should act according to his predominant opinion. This means that if he predominantly thinks that the obstacle occurred before ablution, he should renew his ablution and pray again, but if he predominantly thinks that the obstacle occurred after having performed ablution, then he does not have to repeat the ablution or the prayer.

Nonetheless, if the situation is probable and he cannot predominantly decide, then our opinion, is that he is not obliged to renew the ablution or the prayer. Some jurists stated that if one is not certain if the obstacle which prevents water from reaching the skin (of a limb that must be washed during ablution) happened after having performed ablution or before having done so, then one should consider it to have happened after having performed ablution. They also stated that whoever sees an impurity on his body after having performed the prayer, and does not know whether it occurred before or after the prayer, then his prayer is correct due to the probability that the impurity could have occurred after the prayer.

Prayer and ablution cannot be considered void based on doubts.