´It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:` "Were it not that I would impose too much difficulty on my Ummah, I would have commanded them to delay 'Isha' and to use the Siwak for every prayer."
Hadith ReferenceSunan an-Nasa'i / The Book of the Times (of Prayer) / Hadith: 535
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم