Hadith 7
Chapter 7: Permitting The Usage Of Siwak In The Afternoon For One Who Is Fasting - كتاب الطهارة
أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ مَالِكٍ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لَوْلاَ أَنْ أَشُقَّ عَلَى أُمَّتِي لأَمَرْتُهُمْ بِالسِّوَاكِ عِنْدَ كُلِّ صَلاَةٍ " .
It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:
"Were it not that it would be too difficult for my Ummah, I would have commanded them to use the Siwak at (the time of) every Salah."
Reference : Sunan an-Nasa'i 7
In-book reference : Book 1, Hadith 7