John Gill Commentary Judges 8:9

"And he spake also unto the men of Penuel, saying, When I come again in peace, I will break down this tower." — Judges 8:9 (ASV)

Ver. 9 And he spoke also to the men of Penuel
In a threatening way, as he had spoken to the men of Succoth: saying, when I come again in peace: having conquered all his enemies, and delivered Israel from their bondage, and restored peace and prosperity to them, of which he had no doubt:

I will break down this tower ;
pointing to it and which stood in their city, and in which they placed their confidence; and when he threatened them, boasted of it as their security.