Pseudo-Chrysostom — as excerpted in the Catena Aurea on Mark 9:43-50

“(v. Vict. Ant. in Cat.) Or, according to Matthew, the disciples of Christ are the salt, which preserves the whole world, resisting the rottenness which proceeds from idolatry and sinful fornication. For it may also be meant, that each of us has salt, in as far as he contains in himself the graces of God. Wherefore also the Apostle joins together grace and salt, saying, Let your speech be always with grace, seasoned with salt. (Col. 4:6) For salt is the Lord Jesus Christ, Who was able to preserve the whole earth, and made many to be salt in the earth: and if any of these be corrupted, (for it is possible for even the good to be changed into corruption,) they are worthy to be cast out.”