Sayyiduna Abu Bakr Siddiq (may Allah be pleased with him) says: I was sitting with the Messenger of Allah (peace and blessings be upon him) when a man came who had performed ablution, but there was a spot on his foot that the water had not reached. So the Prophet (peace and blessings be upon him) said to him: "Go and complete your ablution." So he did so.
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