Hope of water is distinct from certainty and a strong probability of nearby water. With credible hope, waiting until a late part of prayer time may be recommended.
Where there is no genuine prospect, there is no need to wait merely for waiting's sake. The prayer must still be completed within its time.
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Tayammum Materials, Intention, Nullifiers, and Searching for Water
Hope of water is distinct from certainty and a strong probability of nearby water. With credible hope, waiting until a late part of prayer time may be recommended.
Where there is no genuine prospect, there is no need to wait merely for waiting's sake. The prayer must still be completed within its time.