Is blaming others a sin?

Exodus 20:16You must not testify falsely against your neighbor.

It may come as a surprise to realize that wrongly blaming others breaks the ninth commandment, which forbids knowingly assigning guilt to a neighbor. This is a kind of lying, and it is sin. It violates the great commandment to love our neighbor as ourselves.

Proverbs 28:13People who conceal their sins will not prosper, but if they confess and turn from them, they will receive mercy.

A primary strategy in concealing our sin is to point at someone else. In these cases, blaming someone else simply adds another layer to our sin. We can be certain that God will not reward this behavior.