Luke 10:6

And if the son of peace be there
If there be any elect person or persons in the house, whom God has chosen to partake of peace by the blood of Christ, and the benefits arising from it; and of a conscience peace in their souls, upon the best foundation; and of eternal peace in the world to come, though yet in a state of nature; and which may be known by this sign;

your peace shall rest upon it:
the salutation, or wish of peace, shall be well taken, and gratefully received; and upon this you will be kindly invited into the house, and used well by, those of the family;

if not, it shall turn to you again:
if there are no sons of peace, no elect persons there, your salutation, or wish of peace and prosperity to the family, will be despised and rejected, and will return to you without any good effect upon them.