Matthew 13:42

Tertullian On the Resurrection of the Flesh

-not even a hair, as also not an eye nor a tooth. And yet whence shall come that "weeping and gnashing of teeth,"[236]

Origen Commentary on Matthew Book X

Then those who become conscious that they have received the seeds of the evil one in themselves, because of their having been asleep, shall wail and, as it were, be angry against themselves; for this is the "gnashing of teeth."[9]

Origen Commentary on Matthew Book X

Only it must be observed, that we are already taught by the parable of the tares and the similitude set forth, that the angels are to be entrusted with the power to distinguish and separate the evil from the righteous; for it is said above, "The Son of man shall send forth His angels, and they shall gather out of His kingdom all things that cause stumbling, and them that do iniquity, and shall cast them into the furnace of fire: there shall be the weeping and gnashing of teeth."[56]