Matthew Poole and continuators on 2 Corinthians 13:12

12 Greet one another with an holy kiss .

See the Notes on Rom. 16.16. 1 Cor. 16.20. 'Twas an ancient custom and of common use, when Friends met, for them (as a token of mutual Love and Friendship) to kiss each other: The Christians use it also at their Ecclesiastical Assemblings: It must not be lookt upon as a Precept, obliging all Christians to do the like; but only as directing those that then did use it, to use it innocently, chastly, sincerely and holily.

Marginal references: 1 Thes. 5.26. 1 Pet. 5.14.