Musnad Ahmad 770:32

'Abd al-Razzaq narrated to us, Ma'mar informed us, from Qatadah, from Humayd ibn Hilal, from Jarir ibn 'Abd Allah al-Bajali, that a man from the Ansar came to the Prophet, peace and blessings of Allah be upon him, with a pouch of gold that filled the space between his fingers, and he said: "This is in the way of Allah, the Mighty and Majestic." Then Abu Bakr, may Allah be pleased with him, stood up and gave, so they gave. Then 'Umar, may Allah be pleased with him, stood up and gave. Then the Muhajirun stood up and gave. He said: The face of the Messenger of Allah, peace and blessings of Allah be upon him, shone until I saw the radiance in his cheeks. Then he said: "Whoever initiates a good practice in Islam and it is acted upon after him, there shall be written for him the like of the rewards of those who acted upon it, without their rewards being diminished in the slightest. And whoever initiates a bad practice in Islam and it is acted upon after him, there shall be written upon him the like of the burdens of those who acted upon it, without their burdens being diminished in the slightest."