On the authority of Ibn ‘Umar (may Allah be pleased with him):

كَانَ لا يَنَامُ إِلا وَالسِّوَاكُ عِنْدَ رَأْسِهِ ، فَإِذَا اسْتَيْقَظَ بَدَأَ بِالسِّوَاكِ

“The Messenger of Allah (ﷺ) did not sleep except the siwaak was at his head. When he woke up he would begin with the siwaak” [Reported by Ahmad and Ibn Nasr graded Hasan by Imam al-Albani in as-Saheeha (no. 2111)]

Imam al-Munaawi (may Allah have mercy upon him) said: “(The Messenger of Allah (ﷺ) did not sleep except the siwaak was at his head due to his intense eagerness for it. (When he woke up he would begin with the siwaak) that is: after he became alert. So that is recommended” [Fayd ul-Qadeer (5/190)]

Translated by

Faisal bin Abdul Qaadir bin Hassan
Abu Sulaymaan