Musnad Ahmad 30:1959

Aswad ibn Amir narrated to us, Sharik narrated to us, from Muhammad—the seller of garments—from his father, from Abu Hurairah, who said: When "A company of the former peoples and a few of the latter peoples" [Al-Waqi'ah: 14] was revealed, that weighed heavily upon the Muslims. Then "A company of the former peoples and a company of the latter peoples" [Al-Waqi'ah: 39] was revealed. He said: "You are one-third of the people of Paradise, nay, you are half of the people of Paradise, and you will share the remaining half with them."