It is narrated from Sayyiduna Anas bin Malik, may Allah be pleased with him, that a man performed ablution and came to the Noble Prophet, peace and blessings be upon him, but there was a spot on his foot, the size of a fingernail, that remained dry. The Messenger of Allah, peace and blessings be upon him, said to him: "Go back and perform ablution properly."

It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that Sayyiduna Umar bin Khattab (may Allah be pleased with him) saw a man who had performed ablution, but a spot the size of a fingernail on the back of his foot remained dry. The Noble Prophet (peace and blessings be upon him) saw him and said: "Go back and perform ablution properly." So he went back, performed ablution again, and then came and offered prayer.

Khalid bin Ma'dan (may Allah have mercy on him) narrates from a Companion of the Messenger that the Messenger of Allah (peace and blessings be upon him) saw a man praying, while an area the size of a dirham on the back of his foot remained dry and water had not reached it. Therefore, the Prophet (peace and blessings be upon him) ordered him to perform ablution again.

It is narrated from Sayyiduna Abu Ruh Kulai’i (may Allah be pleased with him), he says: The Messenger of Allah (peace and blessings be upon him) led us in the Fajr prayer, and he began reciting Surah Rum, but he became hesitant at one verse. When he finished, he said:“The Qur’an is being confused for us, and the reason is that some of those who pray with us do not perform ablution properly. Therefore, whoever wants to pray with us should come after performing ablution well.”

It is narrated from Sayyiduna Abu Ruh Kula'i (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Satan confuses our recitation because some people come to pray without ablution, so when you come for prayer, come after performing ablution properly."