"I said: 'O Messenger of Allah, tell me about Wudu." He said: 'Perform Wudu' well,[1] and exxagerate in sniffing water up into your nose, except when you are fasting.'" [1]See No. 141  

قُلْتُ يَا رَسُولَ اللَّهِ أَخْبِرْنِي عَنِ الْوُضُوءِ قَالَ أَسْبِغِ الْوُضُوءَ وَبَالِغْ فِي الاِسْتِنْشَاقِ إِلاَّ أَنْ تَكُونَ صَائِمًا