Hadithcore
Riyad as-Salihin, 1243

Laqit bin Sabirah (May Allah be pleased with him) reported:

I requested the Messenger of Allah (ﷺ) to talk to me about ablution. He said, "Perform the Wudu' well (by washing those parts of the body, such as the face, hands and feet beyond what is required, like washing the hands up to the upper-arm instead of the elbow). Cleanse the base of your fingers and sniff water deep into the nose except when you are observing fast." <b>[Abu Dawud and At- Tirmidhi]</b>.

وعن لقيط بن صبرة رضي الله عنه قال قلت يا رسول الله أخبرني عن الوضوء‏؟‏ قال‏"‏ ‏"‏أسبغ الوضوء، وخلل بين الأصابع، وبالغ في الاستنشاق، إلا أن تكون صائمًا‏"‏ ‏(‏‏(‏رواه أبوداود، والترمذي وقال‏:‏ حديث حسن صحيح‏)‏‏)‏‏.‏

References1 variant
In-Book Reference
Book 8, Hadith 253
Sharh · explanationclick to expand
<b>Guidance from the Hadith:</b><br> 1) It is Sunnah to sniff water well into the nostrils in ablution, except if a person is fasting, lest water may reach deep inside.<br> 2) Water reaching deep inside through the nose is just like water entering through the mouth; both invalidate the fast.
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