"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." (Using translation from Nasāʾī 7)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ «لَوْلَا أَنْ أَشُقَّ عَلَى أُمَّتِي لَأَمَرْتُهُمْ بِتَأْخِيرِ الْعِشَاءِ وَبِالسِّوَاكِ عِنْدَ كُلِّ صَلَاةٍ»