Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates: I stayed the night with my maternal aunt Maymunah (may Allah be pleased with her). the Messenger of Allah (peace and blessings be upon him) slept, then woke up, performed ablution and used the miswak, and he kept doing so several times throughout the night.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12162
Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that he heard the Prophet (peace and blessings be upon him) say: "The siwak is something that purifies the mouth and pleases the Lord."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12163