Section: If the wounded person performs tayammum for a wound on some of his limbs, then the time [for the prayer] expires, his tayammum becomes void, but his purification with water does not become void if it was an obligatory bath (ghusl) for janabah (major ritual impurity) or similar, because order (tartib) and continuity (muwalat) are not mandatory in that. If it was for wudu, and the wound was on his face, the invalidation of the wudu is derived from the two viewpoints mentioned in the previous section. Whoever makes the order (tartib) mandatory invalidates the wudu here, because the purification of the limb for which the tayammum acted as a substitute has become void, and if the purification of what follows it did not become void, then the purification of what follows it would precede it, and thus the order would be missed. And whoever does not make the order mandatory does not invalidate the wudu, and permits him to perform only the tayammum. If the wound is on one of his feet, or both, then according to the position of one who does not mandate the order between wudu and tayammum, continuity between them is also not mandatory, and he is only obligated to perform the tayammum. And whoever makes the order mandatory, the analogy of his opinion is that there are two viewpoints regarding continuity, based on the continuity in wudu, regarding which there are two narrations: one of them is that it is mandatory, so it is mandatory here, and the wudu is invalidated due to its loss. The second is that it is not mandatory, so the tayammum alone suffices him. It is possible that continuity between wudu and tayammum is not mandatory at all as a single viewpoint, because they are two [types of] purification, so continuity is not required between them, just like other purifications. Also, because making it mandatory entails hardship, which is negated by His saying (the Almighty): "And He has not placed upon you in the religion any difficulty" [Al-Hajj: 78].

Section: If he fears from intense cold, and it is possible for him to heat the water or use it in a way that he is safe from harm—such as washing one limb at a time and covering each part as soon as he washes it—then he is obligated to do so. If he cannot, he performs tayammum and prays, according to the opinion of most scholars. Ata and al-Hasan said: He must perform the full bath, even if he dies, for God has not granted him an excuse. The requirement of the opinion of Ibn Mas'ud is that he should not perform tayammum, for he said: "If we were to grant them a concession in this, it would be likely that one of them, when the water becomes cold for him, would perform tayammum and abandon it."