Whoever was unable to wash a Part of His Body or wipe over it, should make Tayammum for it?

Question :

If a person performed Wudhu', with an injury on his hand, an injury to which water should not reach, so he was going to perform Tayammum for it, but he forgot. Then he prayed without Tayammum, while he was praying he remembered, so he made Tayammum without leaving the prayer and continued to pray. What is the ruling on this prayer, is it invalid, or is it correct?

Answer:

If there is an injury to a part of the body which is normally washed during Wudhu', and he is unable to wash it or wipe over it because it will make the injury worse, or it will delay its healing, then that person must perform Tayammum for it. And whoever made Wudhu', leaving the part of the body which is injured, then prayed, remembering only during the prayer that he had not performed Tayammum, he must make Tayammum and then recommence his prayer (from the beginning), because what he has already prayed before the Tayammum was not correct, including the opening Takbir, because it was not correct for him to begin prayer in the first place, since being in a state of purity is a condition for the correctness of the prayer, and leaving a required part of the body unwashed during Wudhu' or leaving a portion of it unwashed means that the Wudhu' is not correct.

When the Prophet saw a man on whose foot there was a portion the size of a dirham which had not been touched by water, he ordered him to repeat ablution.Since in the case of the questioner it is unfeasible for him to wash or wipe the area, as is required, must proceed to the substitute for it, which is Tayammum; and also due to the generality of Allah's Words:
And if you are ill, or on a journey, or one of you comes after answering the call of nature, or you have been in contact with women (by sexual relations) and you find no water, then perform Tayammum with clean earth and rub therewith your faces and hands.

- and due to the story of the man with the fractured skull: It is reported by Ibn Majah in the narration of Ibn 'Abbas, may Allah be pleased with him, that the Prophet said:
"If he had but washed his body and left his head when it was afflicted by injury".

And in the narration of Abu Dawud, on the authority of Jabir, may Allah be pleased with him, it is reported that he said:
"It would have been enough for him to perform Tayammum"

So if this person who has been asked about has not repeated his prayer, he should do so.