John Chrysostom — as excerpted in the Catena Aurea on Matthew 20:1-16

“That He called not all of them at once, but some in the morning, some at the third hour, and so forth, proceeded from the difference of their minds1. He then called them when they would obey; as He also called the thief when he would obey. Whereas they say, Because no man hath hired us, we ought not to force a sense out of every particular in a parable. Further, it is the labourers and not the Lord who speak thus; for that He, as far as it pertains to Him, calls all men from their earliest years, is shewn in this, He went out early in the morning to hire labourers.”