John Calvin Commentary Matthew 10:13

"And if the house be worthy, let your peace come upon it: but if it be not worthy, let your peace return to you." — Matthew 10:13 (ASV)

If it is not worthy. The meaning of this phrase can be understood as follows: “As their ingratitude makes them unworthy to enjoy the blessing of God which you have prayed for them, break off every bond of communication.”

The word peace refers to the form of greeting commonly used among the Jews. Since the Hebrew word שלום, (shalom,) peace, denotes prosperity, when they wish for someone to be well and happy, and that their affairs may prosper as they wish, they pray that they may have peace.

I acknowledge that the apostles brought to people a different kind of peace, but it is an excessive speculation to interpret this passage as referring to the free reconciliation that takes place between God and people.