Peace be to Heb. shalom, "peace be to you. "The custom of salutation here recommended by our Saviour to his disciples, as St. Jerome informs us, was very prevalent among the Hebrews and Syrians.
This was an ordinary salutation among the Jews, by which they wished happiness and prosperity. (Witham)
These things really baffle the mind. For if the apostles are not to submit to hospitality unless they first inquire who is worthy, how will the house later be found unworthy? And what if the host does not listen to their words and does not receive them? Either there is no fear of this in the wellintentioned person, or, if he is found unworthy, there is no point in sharing his dwelling. And what good will it do to inquire who is worthy if respect and punishment are advised regarding an unworthy host? But the Lord instructs them to desire no part of the home and hospitality of those who either reproach Christ or turn a deaf ear to him. In each town they are to inquire who in the house is worthy, that is, if the church and Christ are inhabitants there, and not to move on to anywhere else if the house is worthy and the host wellintentioned. There would be many Jews with a great affection for the law who, although they might believe in Christ out of admiration for his works, still lingered ...
Do you see how far He declines not to carry His injunctions? And very fitly. For as champions of godliness, and preachers to the whole world, was He training them. And in that regard disposing them to practise moderation, and making them objects of love, He says,