What is the meaning of "They killed him, may Allah kill them! Why did they not ask when they did not know? For indeed, the cure for ignorance is asking. It would have been sufficient for him to perform tayammum, and bind a cloth over his wound, then wipe over it," and should one begin with tayammum or wiping over the cloth, and should one perform wudu before it?

The Prophetic Hadith (definition) "They killed him, may Allah kill them" clarifies that ignorance is a disease and its cure is asking questions. It also shows that the injured man who experienced a wet dream would have only needed to perform tayammum (definition), wrap a cloth bandage around his wound, wipe over it, and wash the rest of his body.

In case of an injury, tayammum must be performed for the injured limb, and it is permissible to wipe over a splint or bandage if it covers a part of the healthy body, while washing the rest of the body. However, if the limb is uncovered, the healthy part should be washed, and tayammum performed for the injured part, without wiping over it. If wiping is not possible, tayammum should be performed.

It is permissible for someone who has performed ghusl (definition) for janabah (definition) (major ritual impurity) to pray without performing wudu, because the intention for purification from the major impurity suffices for wudu.