Abu Hurayrah reported, attributing it to the Prophet ﷺ, "Were it not that I would impose hardship on my community, I would have ordered them to use the siwak before every prayer and to delay the night prayer."
حدثنا سفيان عن أبي الزناد عن الأعرج
يبلغ به النبي ﷺ لولا أن أشق على أمتي لأمرتهم بالسواك عند كل صلاة وتأخير العشاء
Its chain of transmission is sahih. Abu Dawud also related it, 146:1 [Awn al-Mabud], from Qutayba, from Sufyan, with this same chain, though with some parts rearranged. Nasai likewise related it, 1:92-93, from Muhammad bin Mansur, from Sufyan. Muslim related only the ruling on the tooth-stick from it, 1:86-87, from Qutayba, Amr Naqid, and Zuhayr bin Harb, all three from Sufyan. Malik likewise related its beginning in Muwatta, 66, from Abu Zinad. Bukhari related it, 2:311-312, through the route of Malik. He then related it again, 13:195, through another route from Abu Hurairah. Nasai likewise related its beginning, 1:6, through the route of Malik. Ibn Majah related the part about delaying the Isha prayer from it, 690, from Hisham bin Ammar, from Sufyan, and he related its beginning, 287, through another route from Abu Hurairah. Tirmidhi related it in fragments, 1:43, 152, through two other routes. Its meaning will also come again with this same chain within hadith 7338.