كتاب الطهارة
2  
Purity

Yahya related to me from Malik from Ibn Shihab from Humayd ibn Abdar-Rahman ibn Awf that Abu Hurayra said, "Were it not that he would be overburdening his community he (the Messenger of Allah, may Allah bless him and grant him peace,) would have ordered them to use a tooth-stick with each wudu."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ حُمَيْدِ بْنِ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ، عَنْ أَبِي هُرَيْرَةَ، أَنَّهُ قَالَ لَوْلاَ أَنْ يَشُقَّ، عَلَى أُمَّتِهِ لأَمَرَهُمْ بِالسِّوَاكِ مَعَ كُلِّ وُضُوءٍ ‏.‏
USC-MSA web (English) reference : Book 2, Hadith 117
Arabic reference : Book 2, Hadith 146