مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3707
Musnad of Abdullah bin Mas'ood
It was narrated from ‘Abdullah (رضي الله عنه) that The Prophet (ﷺ) said: "The millstone of Islam will turn for thirty-five (years) or thirty-six or thirty-seven, then if they perish (after deviating) they will meet the same fate as those who perished (before them), but if they persist (in following the right path) then they will be in a good state for seventy years." I said: (Seventy years) including that or seventy years in addition to that? He said: “In addition to that."
Musnad Ahmad 3730A hasan hadeeth]