John Chrysostom — as excerpted in the Catena Aurea on Mark 9:1-8

“(Hom. in Matt. 65) Luke in saying, After eight days, does not contradict this; for he reckoned in both the day on which Christ had spoken what goes before, and the day on which he took them up. And the reason that he took them up after six days, was that they might be filled with a more eager desire during the space of these days, and with a watchful and anxious mind attend to what they saw.”