The Prophet ﷺ used to run his fingers through his beard.
أن النبي ﷺ كان يخلل لحيته.
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Tirmidhi (31) and Ibn Majah (430) both narrated it from the hadith of Abdul-Razzaq, from Israil, from Amir bin Shaqiq, from Abu Waail, from Uthman, mentioning the like of it. Its chain is hasan because of Amir bin Shaqiq, for there is disagreement about him, though his hadith is hasan.Hakim (1/149) said, after narrating it through the route of Imam Ahmad bin Hanbal, from Abdul-Razzaq with the same wording, "This is a sahih chain. Both [Bukhari and Muslim] relied on all its narrators except Amir bin Shaqiq, and I do not know of any criticism of Amir bin Shaqiq in any respect."Dhahabi commented on this, saying, "Ibn Main declared him daif, but it has a sahih corroborating witness."I say, it would not be far off to consider his hadith hasan. Tirmidhi said, "hasan sahih." Bayhaqi, in his Sunan (1/54), reported from Bukhari that he was asked about this hadith and said, "It is hasan," and he also said, "The soundest thing I know regarding interlacing the fingers in wudu is the hadith of Uthman." Ibn Khuzayma (151) and Ibn Hibban (1081) also graded it sahih.Tirmidhi reported from Bukhari that he said, the soundest thing on this topic is the hadith of Amir bin Shaqiq, from Abu Waail, from Uthman.