Passage 3.8.6
ἐνέβαλλε δὲ καὶ ἐς τὴν Ἀττικὴν συνεχῶς ὁ Ἆγις στρατιᾷ καὶ ἐπετείχισε φρούριον Ἀθηναίοις τὸ ἐν Δεκελείᾳ· καταλυθέντος δὲ ἐν Αἰγὸς ποταμοῖς τοῦ Ἀθηναίων ναυτικοῦ Λύσανδρος ὁ Ἀριστοκρίτου καὶ Ἆγις ὅρκους μὲν θεῶν ὑπερέβησαν, οὓς ὤμοσαν Ἀθηναίοις ἐν κοινῷ Λακεδαιμόνιοι, κατὰ σφᾶς δὲ αὐτοὶ καὶ οὐ μετὰ Σπαρτιατῶν τοῦ κοινοῦ τὸ βούλευμα ἐς τοὺς συμμάχους ἐξήνεγκαν ἐκκόψαι προρρίζους τὰς Ἀθήνας.
Agis was also continually invading Attica with his army and established a fortress against the Athenians at Decelea. When the Athenian fleet had been destroyed at Aegospotami, Lysander, son of Aristocritus, and Agis violated the oaths sworn before the gods by the Lacedaemonians collectively to the Athenians; and acting on their own initiative, without consulting the common Spartan assembly, they put forward to their allies the decision to destroy Athens utterly from its foundations.