One of the companions of the Prophet ﷺ reported that the Prophet ﷺ saw a man praying with a spot the size of a dirham on the top of his foot that the water had not reached, so the Prophet ﷺ ordered him to repeat the ablution and the prayer.
عن بعض أصحاب النبي ﷺ أن النبي ﷺ رأى رجلا يصلي، وفي ظهر قدمه لمعة قدر الدرهم لم يصبها الماء، فأمره النبي ﷺ أن يعيد الوضوء والصلاة.
Abu Dawud narrated it (175). He said, Haywa bin Shurayh told us, Baqiyya told us, from Buhayr bin Saad, from Khalid, from one of the companions of the Prophet ﷺ, and he related it. Bayhaqi also recorded it (1/83) through the route of Abu Dawud.Its chain is hasan because of Baqiyya, who is Ibn Walid bin Saaid bin Kaab Kalai Himsi, the well known and prolific hadith scholar. He has one hadith in Muslim. He used to practice a great deal of tadlis from weak and unknown narrators, and for that reason, when he uses the form "an" (from), it is not accepted. But when he says "he narrated to us" or "he informed us," he is trustworthy, as Nasai said. He did in fact state explicitly that he heard directly, in the version with Hakim, where he said, "Buhayr narrated to me." This is what Ibn Turkmani said, though I did not find it in the Mustadrak. Ibn Turkmani then said, "The proper course would have been for Bayhaqi to record it through the route of Hakim, so that the hadith would be free of the suspicion attached to Baqiyya."Hafiz said in his Talkhis (1/96), "Athram said, 'I said to Ahmad, "Is this a good chain?" He said, "I would say, if a man from the Tabiin said, 'A man from the companions of the Prophet ﷺ narrated to me,' without naming him, would the hadith be sahih?" He said, "Yes."'Munziri criticized it on the grounds that it contains Baqiyya saying, 'from Buhayr,' and he is a mudallis. But in the Musnad (15495) and the Mustadrak, Baqiyya explicitly stated that he heard it directly, and in it, it reads 'from one of the wives of the Prophet ﷺ.'"Ibn Madini said, "Baqiyya is reliable in what he narrated from the people of Sham, but in what he narrated from the people of Hijaz and Iraq, he is very daif." I say, Buhayr is from Sham. Ahmad said, "There is no one in Sham more reliable than Hurayz, unless it be Buhayr."As for Khalid bin Madan's statement "from one of the companions of the Prophet ﷺ," Hakim said about him (2/600), "Khalid bin Madan is one of the best of the Tabiin. He kept the company of Muaz bin Jabal and other companions after him. So when he attributes a hadith to the companions, its chain is sahih even if the two of them (Bukhari and Muslim) did not record it." End of quote.In this there is a refutation of what Bayhaqi said in Sunan al-Kubra (1/83), after he had recorded the hadith through the route of Abu Dawud, where he said, "It is mursal, though it has also been narrated as a connected hadith." Ibn Turkmani said, "Calling this mursal is not sound, because this Khalid met a group of the companions, and they were all upright, so the fact that one of them is unnamed does not harm the hadith." End of quote.