Abu Hanifa and Muhammad permit tayammum on a pure stone even without a visible film of dust, since stone belongs to the genus of the earth. They read the Quranic expression صَعِيدًا طَيِّبًا
Meaning: Pure earth.
Abu Yusuf's reported position restricts valid substances to soil and sand. Thus a clean stone without dust illustrates the difference.
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Tayammum Materials, Intention, Nullifiers, and Searching for Water
Abu Hanifa and Muhammad permit tayammum on a pure stone even without a visible film of dust, since stone belongs to the genus of the earth. They read the Quranic expression صَعِيدًا طَيِّبًا
Meaning: Pure earth.
Abu Yusuf's reported position restricts valid substances to soil and sand. Thus a clean stone without dust illustrates the difference.