Origen
c. A.D. 184–253
“Likewise also the twelve were reckoned by two and two, as Matthew shews in his enumeration of them. (Matt. 10:2.) For that two should be joined in service, seems from the word of God to be an ancient custom. For God led Israel out of Egypt by the hands of Moses and Aaron. Joshua and Caleb also, united together, appeased the people who had been provoked by the twelve spies. (Numb. 13, 14. Ex. 12.) Hence it is said, A brother assisted by a brother is as a fortified city. (Prov. 18:19. Vulg.)”