It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "When one of you cleans himself with stones (istijmar), let him use an odd number, for Allah is Witr (One) and loves what is odd. Do you not see that the heavens are seven, the days (of the week) are seven, the earths are seven, and the circuits of tawaf and the pebbles of the Jamarat are also seven?" And he (peace and blessings be upon him) mentioned some other things.
No one narrated this hadith from Abu Amir al-Khazzaz except Rawh bin Ubadah (may Allah have mercy on him), and Ibrahim bin Bistam (may Allah have mercy on him) is alone in narrating it.
Hadith Referenceالمعجم الأوسط / باب الميم / 7412
Hadith Takhrij«أخرجه ابن خزيمة فى «صحيحه» برقم: 77، وابن حبان فى «صحيحه» برقم: 1437، والحاكم فى «المستدرك» برقم: 565، والبيهقي فى «السنن الكبرى» برقم: 512، والبزار فى «مسنده» برقم: 9330، وعبد الرزاق فى «مصنفه» برقم: 9803»