John the Apostle
2 John 1:11BSB·traditional attribution

Whoever greets such a person shares in his evil deeds.

Matthew Henry Presbyterian @wholebiblehenry

Here, I. Upon due warning given concerning seducers, the apostle gives direction concerning the treatment of such. They are not to be entertained as the ministers of Christ. The Lord Christ will distinguish them from such, and so would he have his disciples. The direction is negative. 1.

Commenting on 2 John 1:10-11

John Gill Reformed Baptist @doctorgill

For he that biddeth him God speed,.... Wishes him well, and success in his ministry, or in a friendly and familiar way converses with him: is partaker of his evil deeds; he has fellowship with him, instead of reproving or shunning him, as he ought; he is an abettor of him in his principles, and so far joins in the propagation of them, and helps...

Albert Barnes Presbyterian @notesbybarnes

Verse 11. For he that biddeth him, God speed, is partaker of his evil deeds. Shows that he countenances and approves of the doctrine which is taught. Comp. . (+) "speed" "wisheth him success" (b) "partaker"