Imam Malik (may Allah have mercy on him) was asked: If a person in a state of major impurity (janabah) needs to perform tayammum but finds only salty earth, earth mixed with salt, should he perform tayammum with it? And is it disliked to pray on it?
Imam Malik (may Allah have mercy on him) replied: There is no harm in performing tayammum with salty or salt-mixed earth, nor in praying on it, because Allah the Exalted has said: «﴿فَتَيَمَّمُواصَعِيدًاطَيِّبًا﴾». So, intend to use pure earth, and whatever is called earth may be used for tayammum, even if it is salty or something else.
It is narrated from Abdur Rahman bin Harmalah that a person asked Saeed bin Musayyib, "If a person in a state of major ritual impurity (janabah) performed tayammum and then found water, what should he do?" Saeed replied, "When he finds water, then ghusl becomes obligatory upon him for the future."
Imam Malik, may Allah have mercy on him, said: If a person experiences a wet dream while traveling and has with him only enough water for ablution, and he fears thirst, then he should wash his private parts and any impurity that has come upon him with that water, then perform tayammum with clean earth, as Allah, the Glorious and Exalted, has commanded him.
Hadith Referenceموطا امام مالك رواية يحييٰ / كتاب الطهارة / 122
Hadith Gradingمحدثین:مقطوع صحيح
Hadith Takhrij«مقطوع صحيح، أخرجه عبد الرزاق فى «مصنفه» برقم: 891، شركة الحروف نمبر: 113، فواد عبدالباقي نمبر: 2 - كِتَابُ الطَّهَارَةِ-ح: 92»