John Gill Commentary 1 Corinthians 16:20

"All the brethren salute you. Salute one another with a holy kiss." — 1 Corinthians 16:20 (ASV)

All the brethren greet you
Either the brethren, the members of the church at Ephesus; or the apostle's brethren in the ministry, that were along with him, as Sosthenes and others; or the brethren that were come to him from Corinth, namely Stephanas, Fortunatus, and Achaicus:

greet you one another with an holy kiss; (See Gill on Romans 16:16).