It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "Jibril (peace be upon him) kept urging me to use the siwak so much that I began to fear for my teeth."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19814