Pausanias Description of Greece 1.7.1

[1]
  This Ptolemy fell in love with Arsinoe , his full sister, and married her, violating herein Macedonian custom, but following that of his Egyptian subjects. Secondly he put to death his brother Argaeus, who was, it is said, plotting against him; and he it was who brought down from Memphis the corpse of Alexander. He put to death another brother also, son of Eurydice, on discovering that he was creating disaffection among the Cyprians. Then Magas, the half-brother of Ptolemy, who had been entrusted with the governorship of Cyrene by his mother Berenice—she had borne him to Philip, a Macedonians but of no note and of lowly origin—induced the people of Cyrene to revolt from Ptolemy and marched against Egypt .

[1] This Ptolemy, having-conceived-a-passion [ erastheis] for Arsinoe, his full sister, married her, violating Macedonian custom [ nomizomena] in doing so, but following that of his Egyptian subjects. Secondly he put to death his brother Argaios, who was, it is said, plotting against him; and it was he who brought down from Memphis the corpse [ nekros] of Alexander. 35

He put to death another brother also, son of Eurydikē, on discovering that he was creating disaffection among the Cypriotes. Then Magas, the half-brother of Ptolemy, who had been entrusted with the governorship of Cyrene by his mother Berenikē—she had borne him to Philip, a Macedonian but of no note and of lowly origin—induced the people of Cyrene to revolt from Ptolemy and marched against Egypt.