John Lightfoot on Luke 13:7

Behold, these three years I come, &c.] There was no tree that was of a kind to bear fruit might lightly and upon every small occasion be cut down, that law providing against it in Deuteronomy 20:19,20; where the Pesikta observes that there is both an affirmative and also a negative command, by which it is the more forbidden that any tree of that kind should be cut down, unless upon a very indispensable occasion. "Rabh saith, 'Cut not down the palm that bears a cab of dates.' They urge, 'And what of the olive, that that should not be cut down?' 'If it bear but the fourth part of a cab.' R. Chaninah said, My son Shibchah had not died, had he not cut down a fig-tree before its time."

[For more info, please see The Barren Fig-Tree by John Bunyan (140k).]