It was narrated from 'Asim bin Laqit bin Sabrah that his father said:
"I said: 'O Messenger of Allah! Tell me about ablution.' He said: 'Perform ablution properly and sniff water up into your nostrils, thoroughly, unless you are fasting.'" (AR)
English reference (AR): Vol. 1, Book 1, Hadith 407 (AR)
Arabic reference (AR): Book 1, Hadith 441 (AR)