When anyone wipes himself with pebbles (after answering the call of nature) he must make use of an odd number and when any one of you performs ablution he must snuff in his nose water and then clean it. (Using translation from Muslim 237a)
"إذا تَوَضأ أحدُكُمْ فليَجْعَلْ في أنْفِه مَاءً ثُمَّ لينْتَثِرْ وإذا استْجَمْر فَليُوتِرْ".