The Sheikh, may Allah have mercy on him, said: It is stronger in my view that if we say the prayer is not invalidated by seeing water, it is permissible for him to start another prayer. This is because seeing water did not invalidate the tayammum, and if it had been invalidated, the prayer would have been invalidated; nothing has occurred after that which would invalidate it. It is therefore similar to the case if he were to see water with a beast of prey between him and it, then it spilled before the obstacle was removed; he may pray as much as he wishes, just as if he had not seen the water at all.

Section: If he performs tayammum, then sees a caravan and thinks there might be water with them, and we hold the view that seeking is obligatory, or if he sees greenery or something that indicates water in a place where seeking is required, his tayammum is invalidated. Similarly, if he sees a mirage and thinks it is water, his tayammum is invalidated. This is the school of Al-Shafi'i, because once seeking becomes obligatory, the tayammum is invalidated. This applies whether it becomes clear that his suspicion was correct or not. As for seeing the caravan or greenery during the prayer, his prayer and tayammum are not invalidated because he entered into it with a state of certainty of purity, and certainty is not removed by doubt. It is possible that his tayammum is also not invalidated if he is outside of the prayer, because certainty of purity is not invalidated by doubt, just like the purity of water, and the obligation of seeking is not a nullifier of tayammum. Being a nullifier is established only by a legal proof, and there is no text for this here, nor is there any meaning of a text, so the proof is negated.

Section: If the time for the prayer expires while he is still in it, his tayammum is invalidated and his prayer is invalidated, because his purity ended with the expiration of its time, so his prayer is invalidated, just as if the period for wiping over footwear had elapsed while he was in prayer.

Section: Tayammum for a minor impurity is invalidated by everything that invalidates wudu, and in addition by seeing water which one is capable of using, and by the expiration of the time. Some of our companions added: thinking that water exists, as we have mentioned. Some of them also added the case where one removes a turban or a khuff (leather sock) over which it is permissible to wipe; for then his tayammum is invalidated. It is mentioned that Ahmad explicitly stated this, because it is a nullifier of wudu, therefore it invalidates the tayammum, like all other nullifiers of it. The correct view is that this is not a nullifier of tayammum, and this is the position of all the jurists, because tayammum is a purity in which one does not wipe over them, so it is not invalidated by removing them, just like the purity of water, and just as if what was worn was of a type that is not permitted to wipe over.