When Jesus sent out the twelve on what we call the Limited Commission, because they only went to Israelites, Jesus instructed them on how to bless a household that received them,

“Now whatever city or town you enter, inquire who in it is worthy, and stay there till you go out. And when you go into a household, greet it. If the household is worthy, let your peace come upon it. But if it is not worthy, let your peace return to you” (Matthew 10:11–13).

The apostles were ambassadors of peace, for Israel needed it, since the nation stood under the Judgment of God. Likewise, our world is condemned already (John 3:18), now they need us to bring peace into their lives.