Book Section

Alexander could no longer brook the drunken arrogance of Cleitus and leapt up in anger to strike him, but was held back by his boon companions. Still Cleitus did not restrain his insults … No longer could his friends hold him back. He leapt up and, as some say, snatched a spear from one of his guard and therewith struck and slew Cleitus …
Alexander I pity, since he showed himself the slave of two vices, by neither of which should any self-respecting man be overcome, namely, passion and drunkenness. But for the sequel I commend Alexander, in that he immediately perceived that he had done a foul deed …
He took to his bed and lay there lamenting … He lay there three days without food or drink and careless of all other bodily needs …
I have high commendation for Alexander, in that he did not brazen out this evil act, nor degrade himself by becoming champion and advocate oh his misdeed;
but confessed that, being merely human, he had erred.

Arrian (2nd Century AD) - book 4, chapter 8-9. (1929 translation)