Plutarch, Life of Alexander 9.6-11
6 The most open quarrel was brought on by Attalus at the marriage of Cleopatra, a maiden whom Philip was taking to wife, having fallen in love with the girl when he was past the age for it. 7 Attalus, now, was the girl's uncle, and being in his cups, he called upon the Macedonians to ask of the gods that from Philip and Cleopatra there might be born a legitimate successor to the kingdom. 8 At this Alexander was exasperated, and with the words, "But what of me, base wretch? Dost thou take me for a bastard?" threw a cup at him. 9 Then Philip rose up against him with drawn sword, but, fortunately for both, his anger and his wine made him trip and fall. 10 Then Alexander, mocking over him, said: "Look now, men! here is one who was preparing to cross from Europe into Asia; and he is upset in trying to cross from couch to couch." 11 After this drunken broil Alexander took Olympias and established her in Epirus, while he himself tarried in Illyria.