Sayyiduna Ali (may Allah be pleased with him) said: When a person becomes junub (in a state of major ritual impurity) in an open wilderness and he has a little water with him, he should give himself preference with the water (that is, keep it for drinking) and perform tayammum with earth.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1107
Hadith Gradingمحدثین:صحيح لغيرهٖ
Hadith Takhrij«صحيح لغيرهٖ۔ أخرجه ابن أبي شيبة 1118»
Sayyiduna Ali (may Allah be pleased with him) said: "When you become junub (in a state of major ritual impurity) and you intend to perform ablution or ritual bath (ghusl), but you have no water except what you drink, and you fear for your life, then perform tayammum."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1108
It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that: "When you are a traveller and you are junub (in a state of major ritual impurity), or you are without ablution, and you fear that if you perform ablution with the water you will die of thirst, then do not perform ablution; rather, save your life."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1109