Sahih Muslim
The Book Giving Description of the Day of Judgement, Paradise and Hell (Kitab Sifat Al-Qiyamah wal Janna wan-Nar)
Book Number: 039 / Hadith Number: 6698
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).