Barnabas, Barnabas 15
It is also written concerning the Sabbath in the Ten Words, in which God spoke face to face with Moses on Mount Sinai: 'You shall sanctify the Sabbath of the Lord with clean hands and a pure heart' (Exod 20:8-11; Exod 31:13). Elsewhere Scripture says: 'If my sons keep the Sabbath, then I will bestow my mercy upon them.' At the beginning of creation the Sabbath itself declares: 'God made the works of his hands in six days, and on the seventh day he finished, rested, and sanctified it' (Gen 2:2-3). Children, pay close attention to what 'he finished in six days' means: it signifies that in six thousand years the Lord will bring everything to completion, because a day with him represents a thousand years (Ps 90:4; 2 Pet 3:8). He himself bears witness to me, saying: 'Behold, the day of the Lord will be like a thousand years.' Therefore, children, in six days — that is, in six thousand years — all things will be finished. 'And he rested on the seventh day.' This means: when his Son comes, he will abolish the reign of the lawless one, judge the ungodly, and transform the sun, moon, and stars; only then will he truly rest on the seventh day. For it says: 'You shall sanctify it with clean hands and a pure heart.' If anyone now, while still stained by sin, could sanctify the day that God sanctified, we would all be utterly mistaken. See, then, that we will rightly rest and sanctify it only when we ourselves have been justified, have received the promise, when lawlessness is no more, and all things have been made new by the Lord; then, having been sanctified first, we will be able to sanctify it. As he says to them: 'I cannot endure your new moons and Sabbaths' (Isa 1:13). Do you see how he puts it? The present Sabbaths are not acceptable to me; rather, the one I have made — in which, after I have rested, I will bring about the beginning of the eighth day, which is the beginning of another world. That is why we also observe the eighth day with joy, the day on which Jesus rose from the dead, appeared to his disciples, and ascended into the heavens.
Greek
Ἔτι οὖν καὶ περὶ τοῦ σαββάτου γέγραπται ἐν τοῖς δέκα λόγοις, ἐν οἷς ἐλάλησεν ἐν τῷ ὄρει Σινᾶ πρὸς Μωϋσῆν κατὰ πρόσωπον: Καὶ ἁγιάσατε τὸ σάββατον κυρίου χερσὶν καθαραῖς καὶ καρδίᾳ καθαρᾷ. καὶ ἐν ἑτέρῳ λέγει: Ἐὰν φυλάξωσιν οἱ υἱοί μου τὸ σάββατον, τότε ἐπιθήσω τὸ ἔλεός μου ἐπ’ αὐτούς. τὸ σάββατον λέγει ἐν ἀρχῇ τῆς κτίσεως: Καὶ ἐποίησεν ὁ θεὸς ἐν ἓξ ἡμέραις τὰ ἔργα τῶν χειρῶν αὐτοῦ, καὶ συνετέλεσεν ἐν τῇ ἡμέρᾳ τῇ ἑβδόμῃ καὶ κατέπαυσεν ἐν αὐτῇ καὶ ἡγίασεν αὐτήν. προσέχετε, τέκνα, τί λέγει τὸ συνετέλεσεν ἐν ἓξ ἡμέραις. τοῦτο λέγει, ὅτι ἐν ἑξακισχιλίοις ἔτεσιν συντελέσει κύριος τὰ σύμπαντα: ἡ γὰρ ἡμέρα παῤ αὐτῷ σημαίνει χίλια ἔτη. αὐτὸς δέ μοι μαρτυρεῖ λέγων: Ἰδού, ἡμέρα κυρίου ἔσται ὡς χίλια ἔτη. οὐκοῦν, τέκνα, ἐν ἓξ ἡμέραις, ἐν τοῖς ἑξακισχιλίοις ἔτεσιν συντελεσθήσεται τὰ σύμπαντα. Καὶ κατέπαυσεν τῇ ἡμέρᾳ τῇ ἑβδόμῃ. τοῦτο λέγει: ὅταν ἐλθὼν ὁ υἱὸς αὐτοῦ καταργήσει τὸν καιρὸν τοῦ ἀνόμου καὶ κρινεῖ τοὺς ἀσεβεῖς καὶ ἀλλάξει τὸν ἥλιον καὶ τὴν σελήνην καὶ τοὺς ἀστέρας, τότε καλῶς καταπαύσεται ἐν τῇ ἡμέρᾳ τῇ ἑβδόμῃ. πέρας γέ τοι λέγει: Ἁγιάσεις αὐτὴν χερσὶν καθαραῖς καὶ καρδίᾳ καθαρᾷ. εἰ οὖν ἣν ὁ θεὸς ἡμέραν ἡγίασεν νῦν τις δύναται ἁγιάσαι καθαρὸς ὢν τῇ καρδίᾳ, ἐν πᾶσιν πεπλανήμεθα. ἴδε ὅτι ἄρα τότε καλῶς καταπαυόμενοι ἁγιάσομεν αὐτήν, ὅτε δυνησόμεθα αὐτοὶ δικαιωθέντες καὶ ἀπολαβόντες τὴν ἐπαγγελίαν, μηκέτι οὔσης τῆς ἀνομίας, καινῶν δὲ γεγονότων πάντων ὑπὸ κυρίου: τότε δυνησόμεθα αὐτὴν ἁγιάσαι, αὐτοὶ ἁγιασθέντες πρῶτον. πέρας γέ τοι λέγει αὐτοῖς: Τὰς νεομηνίας ὑμῶν καὶ τὰ σάββατα οὐκ ἀνέχομαι. ὁρᾶτε, πῶς λέγει; οὐ τὰ νῦν σάββατα ἐμοὶ δεκτά, ἀλλὰ ὃ πεποίηκα, ἐν ᾧ καταπαύσας τὰ πάντα ἀρχὴν ἡμέρας ὀγδόης ποιήσω, ὅ ἐστιν ἄλλου κόσμου ἀρχήν. διὸ καὶ ἄγομεν τὴν ἡμέραν τὴν ὀγδόην εἰς εὐφροσύνην, ἐν ᾗ καὶ ὁ Ἰησοῦς ἀνέστη ἐκ νεκρῶν καὶ φανερωθεὶς ἀνέβη εἰς οὐρανούς.