Luke 13:6

6.He spoke also this parable. The substance of it is, that many are endured for a time who deserve to be cut off; but that they gain nothing by the delay, if they persist in their obstinacy. The wicked flattery, by which hypocrites are hardened, and become more obstinate, arises from this cause, that they do not think of their sins till they are compelled; and, therefore, so long as God winks at these, and delays his chastisements, they imagine that he is well satisfied with them. Thus they indulge themselves more freely, as if, to use the words of Isaiah, (Isaiah 28:15,) they had made a covenant with death, and were in friendship with the grave. And this is the reason why Paul denounces them in such earnestness of language for

treasuring up to themselves the wrath of God against the last day,
(Romans 2:5.)

It is well known that trees are sometimes preserved, not because their owners find them to be useful and productive, but because the careful and industrious husbandman makes every possible trial and experiment before he determines to remove them out of the field or vineyard. This teaches us that, when the Lord does not immediately take vengeance on the reprobate, but delays to punish them, there are the best reasons for his forbearance. Such considerations serve to restrain human rashness, that no man may dare to murmur against the supreme Judge of all, if He does not always execute his judgments in one uniform manner. A comparison is here drawn between the owner and the vine-dresser: not that God’s ministers go beyond him in gentleness and forbearance, but because the Lord not only prolongs the life of sinners, but likewise cultivates them in a variety of ways, that they may yield better fruit.