Hadith Narrated By Kathir bin Abdullah bin Amr bin Awf Al-Mazini

My father told me, narrating from my grandfather, that the Messenger of Allah (saw) said: 'Whoever revives a Sunnah of mine, will have a reward equivalent to that of those who act upon it, without that detracting from their reward in the slightest. And whoever introduces an innovation (Bid'ah) that is acted upon, will have a burden of sins equivalent to that of those who act upon it, without that detracting from the burden of those who act upon it in the slightest.'" (Daif)