Musnad Ahmad 30:1728

Sulayman narrated to us, Isma'il informed us, al-'Ala' informed me, from his father, from Abu Hurayrah, that the Prophet (peace and blessings of Allah be upon him) said: "Hasten to perform deeds before six [things occur]: the rising of the sun from its place of setting, or the Dajjal, or the smoke, or the beast, or the specific affair of one of you (death), or the general affair (the Hour)."