The Messenger of Allah ﷺ said, "Scrub thoroughly between your fingers and toes during ablution, or the Fire will scrub them."
قال رسول الله ﷺ: لتنهكن الأصابع بالطهور أو لتنهكنها النار.
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Tabarani narrated it in Al-Awsat, Majma Bahrayn (422), from Ibrahim (he is Ibn Ahmad Wakii), who said, Shayban bin Farroukh narrated to us, Abu Awana narrated to us from Abu Miskeen, from Huzayll bin Shurahbil, from Abdullah bin Masud, and he mentioned it. Its chain is hasan because of Abu Miskeen, who is Hurr bin Miskeen Awdi, whom Ibn Main graded thiqah, and Abu Hatim said, "There is no harm in him," Jarh wat-Tadil (3/277). Likewise Shayban bin Farroukh, for his hadith is hasan, and Haythami also graded its chain hasan in Al-Majma (1/236).Tabarani also narrated it in Al-Kabir (9/282) through the route of Thawri and Zaida from Abu Miskeen, with the same chain, but as a mawquf narration. Perhaps one of the narrators related it to him on two separate occasions, once as mawquf and once as marfu, and so neither version invalidates the other.His statement, "you will surely be scoured thoroughly," comes from the root nahaka, and its meaning is to exert exertion in something.As for what has been reported about moving the ring on the finger while washing the hands, it is daif. Ibn Majah narrated it (449), saying, Abdul-Malik Muhammad Raqashi narrated to us, Mamar bin Muhammad bin Ubaydullah bin Abu Rafi narrated to us, my father narrated to me, from Ubaydullah bin Abu Rafi, from his father, that the Messenger of Allah ﷺ, when he performed wudu, would move his ring.Busiri said in Zawaid bin Majah, "Its chain is daif, due to the weakness of Mamar and his father Muhammad bin Ubaydullah." End of quote.I say, it is as he said, for Mamar bin Muhammad transmits alone from his father a body of material, most of which is inverted, and it is not permissible to use it as evidence, as Ibn Hibban said in Kitab Al-Majruhin (3/38). Bukhari said, "His hadith is munkar." Ibn Main said, "He was not among the people of hadith."As for his father, Muhammad bin Ubaydullah bin Abu Rafi, he is daif. Abu Hatim said, "His hadith is daif, extremely munkar, he is discarded." Daraqutni said, "He is matruk, he has problematic narrations."Bayhaqi, after quoting Bukhari's statement about Mamar, said, "Reliance in this matter is on the report from Ali and others." Then he narrated with his chain from Mujammi bin Attab bin Shumayr, from his father, who said, "I helped Ali perform wudu, and whenever he performed wudu he would move his ring."Ibn Turkmani said, "In it is Abdul-Samad Dabbi, whom Ibn Main graded daif, and his teacher Mujammi bin Attab, from his father, I do not know their status."He also narrated with his chain from Azraq bin Qays, who said, "I saw Ibn Umar, whenever he performed wudu, move his ring."Ibn Turkmani said, "In it is Yahya bin Abdul-Hameed Hamani. Bukhari said in Kitab Ad-Duafa, 'They speak critically of him, he narrated from Sharik and others.' Ahmad bin Hanbal said, 'He used to lie openly, we have long known him to steal hadiths.' Muhammad bin Abdullah bin Numayr said, 'A liar.' Juzjani said, 'His hadith has been abandoned.'" End of quote.