Mark 12:2

And at the season he sent to the husbandmen a servant, that he might receive from the husbandmen of the fruits of the vineyard.

At the season ... stands for those particular times when God expected of Israel the fruits of true religion, most of all desiring that they should manifest some consciousness of their need for redemption. God, of course, expected such at all times; but upon special occasions when God sent prophets to Israel, that expectation was more urgent.

A servant ... Cranfield viewed it as inconceivable that Jesus could have taken up the Old Testament figure of God's vineyard and "then speak of the owner sending his slaves one after another without thinking of the prophets."[4]

The fruits of the vineyard... These were the manifestations of Israel's love of God, and particularly their awareness of the need of salvation.