Sunan Ibn Majah Book 1, Hadith 155
"The Messenger of Allah said: 'There is a devil for ablution who is called Walahan, so be on guard against the insinuating thoughts (Waswas) about water.'"
The Messenger of Allah called for water and performed ablution once. He said: "This is the minimum requirement of ablution' or he said: 'The ablution of one who, if he does not perform this ablution, Allah will not accept his prayer." Then he performed ablution washing each part twice, and he said: 'This is the ablution of one who, if he performs it, Allah will give him two shares of reward." Then he performed ablution washing each part three times, and said: 'This is my ablution and the ablution of the Messengers who were sent before me."
A Bedouin came to the Prophet and asked him about ablution. He showed him how to perform it washing each part of the body three times. Then he said: 'This is the ablution, and whoever does more than this, has done evil, transgressed the limits and wronged himself.'"