Messenger of Allah ﷺ said, "I have told you repeatedly to use the Siwak. (The Prophet ﷺ put emphasis on the use of the Siwak.) (Using translation from Bukhārī 888)  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ «أَكْثَرْتُ عَلَيْكُمْ فِي السِّوَاكِ»  

"The Messenger of Allah ﷺ said: 'I have indeed urged you with regard to the Siwak.'" (Using translation from Nasāʾī 6)  

قَالَ رَسُولُ اللَّهِ ﷺ «أَكْثَرْتُ عَلَيْكُمْ فِي السِّوَاكِ»  

[Machine] From the Prophet ﷺ who said, "If it were not a hardship on my Ummah, I would have commanded them to use the siwak (toothstick) at every prayer." Abu Muhammad (one of the narrators) said, "He means the siwak."  

عَنِ النَّبِيِّ ﷺ قَالَ «لَوْلَا أَنْ أَشُقَّ عَلَى أُمَّتِي لَأَمَرْتُهُمْ بِهِ عِنْدَ كُلِّ صَلَاةٍ» قَالَ أَبُو مُحَمَّدٍ يَعْنِي السِّوَاكَ