The Messenger of Allah ﷺ said, "When a dog drinks from one of your vessels, wash it seven times."
أن رسول الله ﷺ قال: إذا شرب الكلب إناء أحدكم فليغسله سبع مرات.
Malik narrated it in Kitab al-Tahara (35) from Abu Zinad, from Araj, from Abu Hurairah, and he mentioned the hadith. Bukhari transmitted it through his route in Kitab al-Wudu (172), and Muslim in Kitab al-Tahara (279).In a narration found in Muslim through the route of Ali bin Mushir, who said, Amash narrated to us, from Abu Razeen and Abu Salih, from Abu Hurairah, it reads, "let him pour it out." He also narrated it through the route of Ismail bin Zakariya, from Amash with this same chain, but he did not say, "let him pour it out." Nasai said (1/53), I do not know of anyone who agreed with Ali bin Mushir in his statement, "let him pour it out." In another narration found in Muslim, it reads, "the first of them with dust."In a narration found in Abu Dawud (73) through the route of Muhammad bin Sirin, from Abu Hurairah, similar to it, with the addition, "the seventh with dust." Abu Dawud said, As for Abu Salih, Abu Razeen, Araj, Thabit al-Ahnaf, Hammam bin Munabbih, and Suddi Abdul-Rahman, they narrated it from Abu Hurairah without mentioning the dust. So the mention of dust in the seventh instance is anomalous, and the preserved wording is "the first of them," which is what Muslim narrated through the route of Muhammad bin Sirin. It appears, then, that whoever added it did so after him.For more, see Minna Kubra (1/237).