The Messenger of Allah ﷺ said, "Were it not that I would impose hardship upon my community, I would have commanded them to use the siwak at every prayer," or "with every prayer."
حدثنا يحيى عن محمد بن عمرو قال حدثنا أبو سلمة
قال رسول الله ﷺ لولا أن أشق على أمتي لأمرتهم بالسواك عند كل صلاة أو مع كل صلاة
Its chain of transmission is sahih. It occurred previously in 9152.