It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The tooth-stick (miswak) purifies the mouth and is pleasing to Allah, the Mighty and Majestic."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7815