´It was narrated that Abu Musa Al-Ash’ari said:` “The Messenger of Allah (ﷺ) said: ‘When the Imam recites, then listen attentively, and if he is sitting (in the prayer) then the first remembrance that anyone of you recites should be the Tashahhud.’”
Hadith ReferenceSunan Ibn Majah / Establishing the Prayer and the Sunnah Regarding Them / Hadith: 847
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم