The Messenger of Allah ﷺ said: The purification of the utensil belonging to any one of you, after it is licked by a dog, lies in washing it seven times, using sand for the first time. (Using translation from Muslim 279d)
قَالَ رَسُولُ اللهِ ﷺ طُهُورُ إِنَاءِ أَحَدِكُمْ إِذَا وَلَغَ فِيهِ الْكَلْبُ أَنْ يَغْسِلَهُ سَبْعَ مَرَّاتٍ أُولَاهُنَّ بِالتُّرَابِ