Tertullian, on 1John 5:16

“He that knoweth his brother to sin a sin which is not to death, let him ask, and life shall be given to him, who sinneth not to death. There is a sin unto death: for that I say not that any man ask.”

“For (in making these assertions) he was looking forward to the final clause of his letter, and for that (final clause) he was laying his preliminary bases; intending to say, in the end, more manifestly: "If any knoweth his brother to be sinning a sin not unto death, he shall make request, and the Lord shall give life to him who sinneth not unto death. For there is a sin unto death: not concerning that do I say that one should make request." He, too, (as I have been), was mindful that Jeremiah had been prohibited by God to deprecate (Him) on behalf of a people which was committing mortal sins.”

Imported from an open dataset — not yet checked against the printed edition.