It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The tooth-stick (miswak) is a means of purifying the mouth and a means of pleasing Allah Almighty."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7713