Passage 2.13.2
Ἵππασος δὲ καὶ οἱ σὺν αὐτῷ διεκελεύοντο ἀμύνεσθαι μηδὲ πολλῶν καὶ ἀγαθῶν ἀμαχεὶ τοῖς Δωριεῦσιν ἀφίστασθαι. προσεμένου δὲ τοῦ δήμου τὴν ἐναντίαν ταύτην γνώμην, οὕτως Ἵππασος σὺν τοῖς ἐθέλουσιν ἐς Σάμον φεύγει. Ἱππάσου δὲ τούτου τέταρτος ἦν ἀπόγονος Πυθαγόρας ὁ λεγόμενος γενέσθαι σοφός· Μνησάρχου γὰρ Πυθαγόρας ἦν τοῦ Εὔφρονος τοῦ Ἱππάσου. ταῦτα μὲν Φλιάσιοι λέγουσι περὶ αὑτῶν, ὁμολογοῦσι δέ σφισι τὰ πολλὰ καὶ Σικυώνιοι.
But Hippasos and those who were with him urged resistance, arguing that they should not yield to the Dorians without fighting for their many and noble possessions. As the people stood firm on the opposite opinion, Hippasos, along with those who were willing, fled to Samos. The fourth descendant of this Hippasos was Pythagoras, who was famed for his wisdom; for Pythagoras was the son of Mnesarchos, the son of Euphron, who was the son of Hippasos. These things the Phliasians relate about themselves, and the Sikyonians agree with them for the most part.