Abu al-Duha said: I heard Sayyiduna Jarir bin Abdullah (may Allah be pleased with him) addressing the people, and it was his habit to go to the pulpit and stand upon it. I heard him say: the Messenger of Allah (peace and blessings be upon him) said: "Whoever introduces a good practice in Islam will have a reward equal to that of those who act upon it, without anything being reduced from their rewards. And whoever introduces an evil practice in Islam will bear a burden of sin equal to that of those who act upon it, without anything being reduced from their sins."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2424