Passage 1.6.2
Πτολεμαῖον Μακεδόνες Φιλίππου παῖδα εἶναι τοῦ Ἀμύντου, λόγῳ δὲ Λάγου νομίζουσι· τὴν γάρ οἱ μητέρα ἔχουσαν ἐν γαστρὶ δοθῆναι γυναῖκα ὑπὸ Φιλίππου Λάγῳ. Πτολεμαῖον δὲ λέγουσιν ἄλλα τε ἐν τῇ Ἀσίᾳ λαμπρὰ ἀποδείξασθαι καὶ Ἀλεξάνδρῳ κινδύνου ξυμβάντος ἐν Ὀξυδράκαις μάλιστά οἱ τῶν ἑταίρων ἀμῦναι. τελευτήσαντος δὲ Ἀλεξάνδρου τοῖς ἐς Ἀριδαῖον τὸν Φιλίππου τὴν πᾶσαν ἄγουσιν ἀρχὴν ἀντιστὰς αὐτὸς μάλιστα ἐγένετο ἐς τὰς βασιλείας αἴτιος τὰ ἔθνη νεμηθῆναι.
The Macedonians say that Ptolemy was the son of Philip, the son of Amyntas, though nominally he was considered the son of Lagus; for his mother, already pregnant, was given in marriage by Philip to Lagus. They say further that Ptolemy distinguished himself notably by significant achievements in Asia, and especially amongst Alexander's companions protected him when he was in danger among the Oxydracae. After Alexander's death, Ptolemy strongly opposed those assigning full power to Arrhidaeus, Philip's son, and was particularly instrumental in causing the division of nations into separate kingdoms.