On the authority of Abu Hurayrah, from the Prophet ﷺ, who said: "Whoever applies kohl, let him do so an odd number of times. Whoever does so has done well, and whoever does not, there is no harm. Whoever uses stones for cleansing, let him use an odd number. Whoever does so has done well, and whoever does not, there is no harm. Whoever eats and has food stuck between his teeth, let him spit it out, and whatever he works with his tongue, let him swallow it. Whoever does so has done well, and whoever does not, there is no harm. Whoever goes to relieve himself, let him conceal himself, and if he finds nothing but to gather a mound of sand, let him turn his back to it, for the devil plays with the posteriors of the children of Adam. Whoever does so has done well, and whoever does not, there is no harm."

Abu Dawud said: Abu 'Asim narrated it from Thawr, who said: "Husayn al-Himyari." And 'Abd al-Malik ibn al-Sabbah narrated it from Thawr, and he said: "Abu Sa'd al-Khayr."

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(1) Its chain is weak; Husayn al-Habrani is unknown, and only Thawr ibn Yazid al-Himsi narrated from him. And Abu Sa'id—also said Abu Sa'd—who is al-Habrani, is also unknown; only Husayn al-Habrani narrated from him.
It was also recorded by Ibn Majah (337) and (338), and in abbreviated form (3498) via the route of 'Abd al-Malik ibn al-Sabbah, from Thawr ibn Yazid, with this chain.
It is in "Musnad Ahmad" (8838), and "Sahih Ibn Hibban" (1410).
(2) He is al-Dahhak ibn Makhlad, known as al-Nabil, and his narration is found in al-Darimi (662) and (2087), al-Tahawi in "Sharh al-Ma'ani" 1/122, and in "Sharh al-Mushkil" (138), Ibn Hibban (1410), and al-Hakim 4/137.
(3) His narration is found in Ibn Majah (337), and we have noted there that his statement "Abu Sa'd al-Khayr" is a mistake.
(4) Ibn Dasah added in his narration: Abu Dawud said: Abu Sa'd al-Khayr is one of the companions of the Prophet ﷺ.