John Calvin Commentary Hebrews 13:24

"Salute all them that have the rule over you, and all the saints. They of Italy salute you." — Hebrews 13:24 (ASV)

Salute, etc. Since he writes his Epistle generally to the Hebrews, it is strange that he instructs some, separate from the rest, to be greeted; but he sends this greeting, I believe, more particularly to the rulers as a mark of honor, so that he might conciliate them and gently lead them to assent to his doctrine. And he adds:

And all the saints. He either means the faithful from among the Gentiles, and refers to them so that both Jews and Gentiles might learn to cultivate unity among themselves; or his purpose was to suggest that those who first received the Epistle were to communicate it to others.