Sahih Muslim Book 39, Hadith Number 6698.
Chapter : Description of the day of judgement, paradise and hell.
Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: A bulky person would be brought on the Day of judgment and he would not carry the weight to the eye of Allah equal even to that of a gnat. Nor shall We set up a balance for them on the Day of Resurrection” (xviii. 105).