The burden and heat of the day - The burden means the heavy labor, the severe toil. We have continued at that toil in the heat of the day. The others had worked only a little while, and that in the cool of the evening, and when it was fax more pleasant and much less fatiguing.
Related Commentaries of Matthew 20:12
Matthew 20:12
12 Saying, These last have wroughtb but one hour, and thou hast made them equal unto us, which have borne the burden and heat of the day.