Musnad Ahmad 8:26

'Isam ibn Khalid narrated to us, Abu Bakr—meaning Ibn Abi Maryam—narrated to me, from Rashid ibn Sa'd, from Sa'd ibn Abi Waqqas, from the Prophet, may Allah bless him and grant him peace, that he used to say: "My nation will not be unable before my Lord to delay them for half a day." And I asked Rashid: "Has it reached you what the half day is?" He said: "Five hundred years."