Augustine of Hippo
Catena Aurea · Markusevangelium 9
And if thy hand offend thee, cut it off: it is better for thee to enter into life maimed, than having two hands to go into hell, into the fire that never shall be quenched: Where their worm dieth not, and the fire is not quenched. And if thy foot offend thee, cut it off: it is better for thee to enter halt into life, than having two feet to be cast into hell, into the fire that never shall be quenched: Where their worm dieth not, and the fire is not quenched. And if thine eye offend thee, pluck it out: it is better for thee to enter into the kingdom of God with one eye, than having two eyes to be cast into hell fire: Where their worm dieth not, and the fire is not quenched. For every one shall be salted with fire, and every sacrifice shall be salted with salt. Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves, and have peace one with another.
(de Con. 4. 6) Mark relates that the Lord said these things consecutively, and has put down some things omitted by every other Evangelist, some which Matthew has also related, others which both Matthew and Luke relate, but on other occasions, and in a different series of events. Wherefore it seems to me that our Lord repeated in this place discourses which He had used in other places, because they were pertinent enough to this saying of His, by which He prevented their forbidding miracles to be wrought in His name, even by him who followed Him not together with His disciples.