The Prophet ﷺ drank some milk, then called for water and rinsed his mouth, saying, "It has greasiness to it."
أن النبي ﷺ شرب لبنا، ثم دعا بماء فتمضمض، وقال: إن له دسما.
Bukhari narrated it in the Book of Drinks (5609), and Muslim in the Book of Menstruation (358), both of them through Zuhri, from Ubaydullah bin Abdullah, from Ibn Abbas, who mentioned it.