Adam Clarke on Matthew 20:1

For the kingdom of heaven is like unto a man - a householder - The very commencement of this chapter shows it to be connected with the preceding. The manner of God's proceeding under the Gospel dispensation resembles a householder, who went out at day break, αμα πρωι, together with the morning; as the light began to go out of its chambers in the east, so he went out of his bed-room to employ laborers, that they might cultivate his vineyard. This was what was called, among the Jews and Romans, the first hour; answering to six o'clock in the morning.

To hire laborers - Some workmen, των εργατων - for he had not got all that was necessary, because we find him going out at other hours to hire more.