Sunan an-Nasa'i 7
Sahih Graded by Abu Ghuddah Book of The Book of Purification · Hadith 7 of 5,758أَخْبَرَنَا 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 " .
Narrated by Abu Hurairah
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
References
Sunan an-Nasa'i 7
In-book: Book 1, Hadith 7 Source: hadith-api (fawazahmed0)