Zechariah 8:16: Speak Truth to Your Neighbor
Zechariah 8:16 does not ask God's people to talk honestly so that he will decide to bless them. It tells them to speak truth because he has already decided to do good, and their speech is meant to match his kindness.
Ephesians 4:25: Speak Truth to Your Neighbor
Ephesians 4:25 ties truthful speech to our new identity in Christ and to our shared life in the body. Lying is not just a private flaw; it damages the neighbors we belong to.