Musnad Abu Ya'la al-Mawsili 153:49

Abu Khaythama narrated to us, Hibban ibn Hilal narrated to us, Shu'bah narrated to us, he said: 'Asim ibn 'Ubayd Allah informed me, he said: I heard Salim narrating from Ibn 'Umar, that Ibn 'Umar said: "O Messenger of Allah, do you see what we do: is it in a matter that has already been finished, or in a matter that is newly begun or initiated?" He said: "In that which has already been finished" — Shu'bah doubted regarding it — "Work, O son of al-Khattab, for everyone is facilitated. As for whoever is among the people of felicity, he works for felicity, and whoever is among the people of wretchedness, he works for wretchedness."