Musnad Ahmad 1013:39

Yazid narrated to us, Abu Ghassan Muhammad ibn Mutarrif informed us, from Abu Hazim, from Sahl ibn Sa’d, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, a man may perform the deeds of the people of the Fire while he is among the people of Paradise, and a man may perform the deeds of the people of Paradise while he is among the people of the Fire. And indeed, deeds are only by their endings."