He traced it back to the Prophet ﷺ, "When any of you cleans himself with stones, let him use an odd number, for Allah is One and loves what is odd."
حدثنا سفيان عن أبي الزناد عن الأعرج
يرفعه إذا استجمر أحدكم فليستجمر وترا فإن الله وتر يحب الوتر
Its isnad is sahih. This hadith was not mentioned in the printed edition h, perhaps it was accidentally omitted by a copyist or printer. It is established in manuscripts l and m. So we have included it here, placing it between the two addition marks. I have not found it with this wording and context except in what I will mention, although its meaning is established as sahih through many routes.The closest wording to this context is what Bayhaqi related in Sunan al-Kubra 1:104, through the route of Harith bin Abu Usama, who said Rawh bin Ubada narrated to us, Abu Amir Khazzaz narrated to us, from Ataa, from Abu Hurairah, that the Prophet ﷺ said, "When one of you cleans himself with stones, let him use an odd number, for Allah loves the odd number. Do you not see the seven heavens, the seven earths, tawaf," and he mentioned other things.Haythami mentioned it with this wording, the wording of Bayhaqi, in Majma al-Zawaid 1:211, and he said in it, "and tawaf seven times," since the word "seven" was not mentioned along with tawaf in Bayhaqi's narration. Haythami said, "Bazzar related it, and Tabarani in al-Awsat, adding, 'and the pebbles [of stoning],' and its narrators are the narrators of the sahih." I do not have Bazzar's isnad or Tabarani's isnad at hand, but it appears to me that both of them related it through the same route through which Bayhaqi related it.As for its meaning, it comprises two meanings, the command to clean oneself with stones in an odd number, and that Allah is odd and loves the odd number. Both meanings are established as sahih, from the hadith of Abu Hurairah and from the hadith of others as well.As for the command to clean oneself with stones in an odd number, this has already passed within hadith 7220, through the route of Malik, from Zuhri, from Abu Idris, from Abu Hurairah, as a raised hadith, "Whoever cleans himself with stones, let him use an odd number." It is found in Muwatta and Sahihayn, as we mentioned there. Malik also related it 19, within a hadith, from Abu Zinad, from Araj, from Abu Hurairah. It will also come again at 7732, through the route of Malik, from Abu Zinad. It will also come again at 9970, through the narration of Waki, from Thawri, from Abu Zinad. Likewise it will come again at 7445, through the narration of Abdul-Rahman bin Ishaq, from Abu Zinad, from Araj, from Abu Hurairah, in abbreviated form, with the wording, "When one of you cleans himself with stones, let him use an odd number." It will also come again at 8596 and 8662, within a hadith, through the route of Ibn Lahia, from Abu Yunus Salim bin Jubayr, the freed slave of Abu Hurairah, from Abu Hurairah, with the wording, "When he cleans himself with stones, let him clean himself with an odd number." It will also come again with its meaning, through many routes from Abu Hurairah, at 7716, 8013, 8150, 8710, 8825, 9017, 9199, 10257, 10729.As for his saying, "Allah is odd and loves the odd number," it will come again at 7717, 7883, 10376, through the narration of Ibn Sirin from Abu Hurairah, and at 7718 through the narration of Hammam bin Munabbih from him. It will also come again within a hadith, through the narration of Hammam as well, at 7612, 8131. It will likewise come again within a hadith, through the narration of Muhammad bin Ishaq from Abu Zinad, from Araj, from Abu Hurairah, at 7493. It has also already passed, from the hadith of Ibn Umar, at 5880, 6439.