The most commanded one another is to love one another. You can't love one another if you lie to one another. There's plenty of reasons why we lie; maybe it's for the applause of man or maybe it's to keep parts of our lives in the dark. But Jesus died on the cross so we can live in light of the gospel and walk in the freedom Christ came to give us.

⁹ Do not lie to one another, seeing that you have put off the old self with its practices ¹⁰ and have put on the new self, which is being renewed in knowledge after the image of its creator. - Colossians 3:9-10