John Mark
Mark 6:7BSB·traditional attribution

Then Jesus called the Twelve to Him and began to send them out two by two, giving them authority over unclean spirits.

Matthew Henry Presbyterian @wholebiblehenry

Here is, I. The commission given to the twelve apostles, to preach and work miracles; it is the same which we had more largely, Mt. 10. Mark doth not name them here, as Matthew doth, because he had named them before, when they were first called into fellowship with him, Mar 3:16-19.

Commenting on Mark 6:7-13

John Gill Reformed Baptist @doctorgill

And he called unto him the twelve,.... "His twelve disciples", as some copies read; whom he had before called by his grace, and had appointed and ordained them his apostles, but had not yet publicly sent forth; in order to which, he now called them to him, and gave them their commission, qualifications, and instructions: and began to send them forth by two and two...

Albert Barnes Presbyterian @notesbybarnes

Verse 7. By two and two. In order that they might support and encourage each other in their work. Amidst the trials and opposition which they would meet with, mutual counsel and aid would greatly lighten their burdens, and alleviate their calamities. Mutual counsel might also contribute to their success, and lead to united plans to advance the kingdom of the Redeemer.