On the authority of his father, who said: I said, “O Messenger of Allah, tell me about the ablution (wudu).” He said: “Perform the ablution thoroughly, and run water between the fingers, and snuff water deeply into the nose, unless you are fasting.”¹

This is a good and authentic hadith.

The people of knowledge have disapproved of snuffing medicine into the nose² for the one who is fasting, and they held that this breaks his fast. In this hadith there is what strengthens their opinion.

70 – Chapter: What has come concerning one who alights with a people, that he should not fast except with their permission

799 – Bishr ibn Mu‘adh al-‘Aqadi al-Basri narrated to us, saying: Ayyub ibn Waqid al-Kufi narrated to us, from Hisham ibn ‘Urwah, from his father, from ‘A’ishah, who said: The Messenger of Allah, peace and blessings be upon him, said: “Whoever alights with a people, let him not observe a voluntary fast except with their permission.”³

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¹ A sound hadith, also transmitted in full and abridged form by Abu Dawud (142), (143), and (2366); Ibn Majah (407) and (448); al-Nasa’i 1/66 and 79, and in al-Kubra (98/m), (117), and (3047); it is in al-Musnad (16380), and Sahih Ibn Hibban (1054) and (1087).
² It is said: sa‘atuhu and as‘atuhu, so he snuffed it; the noun is al-sa‘ut with a fatha, which is what is placed as medicine in the nose. “Al-Nihayah.”
³ Its chain of transmission is very weak because of Ayyub ibn Waqid al-Kufi, for he is abandoned in hadith. Ibn ‘Adi transmitted it in al-Kamil 1/348 via the route of Mubashshir ibn Mu‘adh, with this chain. Ibn Majah transmitted it (1763) via the route of Musa ibn Dawud and Khalid ibn Abi Yazid, both from Abu Bakr al-Madani, from Hisham ibn ‘Urwah, with it — this being the route to which he pointed.