The disciple is not above his master: but every one that is perfect shall be as his master. Every one that is perfect - Or, thoroughly instructed, κατηρτισμενος: - from καταρτιζω, to adjust, adapt, knit together, restore, or put in joint. The noun is used by the Greek medical writers to signify the reducing a luxated or disjointed limb. It sometimes signifies to repair or mend, and in this sense it is applied to broken nets, Matthew 4:21; Mark 1:19; but in this place, and in Hebrews 13:21; 2 Timothy 3:17, it means complete instruction and information. Every one who is thoroughly instructed in Divine things, who has his heart united to God, whose disordered tempers and passions are purified and restored to harmony and order; every one who has in him the mind that was in Christ, though he cannot be above, yet will be as, his teacher - holy, harmless, undefiled, and separate from sinners.
"The disciple who perfectly understands the rules and sees the example of his master, will think it his business to tread exactly in his steps, to do and suffer upon like occasions, as his master did: and so he will be like his master." Whitby.