John Gill Commentary Zechariah 3:6

"And the angel of Jehovah protested unto Joshua, saying," — Zechariah 3:6 (ASV)

And the Angel of the Lord protested unto Joshua, saying .
] He not only gave his word, but annexed his oath; he called as it were heaven and earth to witness; and this he did to confirm the faith of Joshua in the promises he was about to make, as well as in the blessings of grace bestowed upon him; as the pardon of his sins, the justification of his person, and acceptance with God.