Sahih Muslim Book 2, Hadith Number 462.

Chapter : While cleaning the nose and using of pebbles in the toilet, the odd number is preferable.

Abu Huraira reported: The Apostle of Allah (may peace be upon him) said: When any one of you awakes up from sleep and performs ablution, he must clean his nose three times, for the devil spends the night in the interior of his nose.