Musnad Ahmad 27:1507

Al-Fadl ibn Dukayn narrated to us, Sharik narrated to us, I heard Salamah ibn Kuhayl narrating from Mujahid, from Ibn Umar, who said: We were sitting with the Prophet, peace and blessings of Allah be upon him, and the sun was over [the mountain of] Qu'ayqi'an after the afternoon [Asr] prayer. He said: "Your lifespans in comparison to the lifespans of those who have passed are only like what remains of the day in comparison to what has passed of it."