with the head, the chest, the back, the lower part of the body, or by plunging into a pool and emerging from it with the intention of performing the bath.

Performing ablution in conjunction with the major bath is recommended but not obligatory. It is sunnah to make ablution before beginning the bath, and once the bath is complete there is no need to repeat the ablution, for nothing authentic shows that the Prophet—peace and blessings be upon him—ever performed a second ablution after bathing.

If water cannot be found, or a person is ill and fears harm from using it, or the weather is bitterly cold and he has nothing with which to warm the water, he should perform tayammum. Allah the Exalted says:
“ And if you are sick or on a journey, or if one of you has relieved himself, or you have had intimate contact with women, and you find no water, then perform tayammum with clean earth and wipe your faces and hands with it. Allah does not wish to place you in hardship; rather, He wishes to purify you and perfect His favor upon you, so that you may be grateful.” (Q 5:6)
Thus, Allah made it clear that during travel and illness one resorts to tayammum when water cannot be found while traveling.

As for the fear of severe cold, its evidence is the story of ʿAmr ibn al-ʿĀṣ—may Allah be pleased with him: “The Prophet, peace and blessings be upon him, dispatched him on an expedition. He entered a state of major impurity, so he performed tayammum and led his companions in prayer. When they returned, the Prophet said to him, ‘O ʿAmr, did you lead your companions in prayer while you were junub?’ He replied, ‘Yes, O Messenger of Allah! I remembered Allah’s words, “Do not kill yourselves; surely Allah is ever Merciful to you” (Q 4:29), so I feared the cold, performed tayammum with clean earth, and prayed.’” The Prophet approved his action and did not order him to repeat the prayer, because one who fears harm is treated like one who is actually harmed—provided that the fear is predominant or certain, whereas mere