Albert Barnes Commentary Zechariah 13:5

"but he shall say, I am no prophet, I am a tiller of the ground; for I have been made a bondman from my youth." — Zechariah 13:5 (ASV)

And he shall say - Repudiating his former claims, I am a husbandman: for a man has taught me from my youth. There was no room then for his having been a false prophet, since he had had from his youth one simple unlettered occupation, as Amos said truly of himself; I was no prophet, neither was I a prophet’s son: but I was an herdsman and a gatherer of sycamore fruit (Amos 7:14). The prophet does not approve the lie, any more than our Lord did the injustice of the unjust steward. Our Lord contrasted the wisdom in their generation of a bad man for his ends, with the unwisdom of the children of light, who made no effort to secure their God. Zechariah pictures vividly, how people would in any way rid themselves of all suspicion of false prophesying.