Deuteronomy 32:4
He is the Rock, his work is perfect: for all his ways are judgment: a God of truth and without iniquity, just and right is he.
Torrey's Topical Textbook—AKJV

Isaiah 65:16
That he who blesses himself in the earth shall bless himself in the God of truth; and he that swears in the earth shall swear by the God of truth; because the former troubles are forgotten, and because they are hid from my eyes.
Torrey's Topical Textbook—AKJV