Sunan Ibn Majah 206

It was narrated from Abu Hurairah that:The Messenger of Allah said: "Whoever calls people to true guidance, will have a reward equal to that of those who follow him, without that detracting from their reward in the slightest. And whoever calls people to misguidance, will have a (burden of) sin equal to that of those who follow him, without that detracting from their sins in the slightest