The Epistle of Barnabas and the End of the World

You can file this under “Nothing New Under the Sun”:

Furthermore, concerning the sabbath it is also written, in the Ten Words that he spoke to Moses face to face on Mount Sinai: “And sanctify the Lord’s sabbath, with clean hands and a clean heart.” And in another place he says: “If my children guard the sabbath, then I will bestow my mercy upon them.” He speaks of the sabbath at the beginning of the creation: “And God made the works of his hands in six days, and finished on the seventh day, and rested on it, and sanctified it.” Observe, Children, what “he finished in six days” means. It means this: that in six thousand years the Lord will bring everything to an end, for with him a day signifies a thousand years. And he himself bears me witness when he says, “Behold, the day of the Lord will be as a thousand years.” Therefore, children, six days–that is, in six thousand years–everything will be brought to an end. “And he rested on the seventh day.” This means: when his son comes, he will destroy the time of the lawless one and will judge the ungodly and will change the sun and the moon and the stars, and then he will truly rest on the seventh day. (Barnabas 15:1-5)

The Apostolic Fathers: Greek Texts and English Translations 3rd Ed. Trans Michael W. Holmes.