This is another article in the chapter Enormities from the classical manual on Sharia called Reliance of the Traveller. The articles are posted one by one in the order they are given in the book.
p58.0 HE WHO INAUGURATES A REPREHENSIBLE INNOVATION (BID’A) (def: w29.3)
p58.1 The Prophet (Allah bless him and give him peace) said:
(1) “He who calls others to misguidance is guilty of a sin equal to the sins of all who follow him therein without this diminishing their own sins in the slightest.”
(2) “He who inaugurates a good sunna [custom] in Islam earns the reward of it and of all who perform it after him without diminishing their own rewards in the slightest. And he who introduces a bad sunna is guilty of the sin of it and of all who perform it after him without diminishing their own sins in the slightest.”