A.T. Robertson Commentary 1 Thessalonians 5:26

"Salute all the brethren with a holy kiss." — 1 Thessalonians 5:26 (ASV)

With a holy kiss (εν φιληματ αγιω). With a kiss that is holy (Milligan) a token of friendship and brotherly love (1 Corinthians 16:20; 2 Corinthians 13:12; Romans 16:16). In 1 Peter 5:14 it is "with a kiss of love." This was the customary salutation for rabbis.