Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: Whenever the Prophet (peace and blessings be upon him) slept, the miswak was with him, and when he woke up, the first thing he did was use the miswak.
Ahmad and Abu Ya'la recorded it. Some of its routes have these words: "In whatever part of the night the Prophet (peace and blessings be upon him) woke up, he would use the miswak." Al-Tabarani recorded it likewise in al-Mu'jam al-Kabir. Its chain is da'if (weak); some of its routes contain a narrator who is not named, some contain a narrator named Husam bin Missak, and there are other narrators as well.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2560