Ἀλεξάνδρου ἀνάβασις 4.24.8

4.24.8

καὶ ἐν τούτῳ Πτολεμαῖος ὁ Λάγου ἐκπεμφθεὶς μὲν ὑπὸ Ἀλεξάνδρου ἐς προνομήν, προελθὼν δὲ προσωτέρω αὐτὸς ξὺν ὀλίγοις ὡς ἐς κατασκοπήν, ἀπαγγέλλει Ἀλεξάνδρῳ πυρὰ κατιδεῖν τῶν βαρβάρων πλείονα ἤ ἐν τῷ Ἀλεξάνδρου στρατοπέδῳ.

Meanwhile Ptolemy, the son of Lagos, who had been sent out by Alexander to procure forage, and had gone with a few followers a considerable distance in advance to reconnoitre the enemy, came back to Alexander to report that he had seen more fires where the barbarians were posted than in Alexander's camp. Alexander, without believing that the fires were so numerous, was still convinced that a host of barbarians had mustered together from the surrounding country, and therefore leaving a part of his army where it was encamped in proximity to the mountain, he took with him such a force as the reports led him to think would be adequate, and when the fires were near in view, he divided it into three parts. The command of one part he gave to Leonnatos, an officer of the bodyguard, placing under him the brigade of Attalos, along with that of Balakros. The command of the second division he gave to Ptolemy, the son of Lagos. It consisted of a third of the royal hypaspists, together with the brigade of Philippos and Philotas, two companies of archers, each a thousand strong, the Agrians, and half of the horsemen. The third division Alexander led in person against the position occupied by the main body of the barbarians.