Adam Clarke's Commentary on the Bible - Jude 1:5
I will therefore put you in remembrance - That is, how such persons were proscribed, and condemned to bear the punishment due to such crimes. Though ye once knew this - The word ἁπαξ , here translated once, has greatly puzzled many interpreters. It has two meanings in the sacred writings, and indeed in the Greek writers also. It signifies once, one time, as opposed to twice, or several times. Altogether, entirely, perfectly, interpreted by Suidas αντι τον διολου, ὁλοσχερως· ... read more
Adam Clarke's Commentary on the Bible - Jude 1:4
For there are certain men crept in unawares - Παρεισεδυσαν· They had got into the Church under specious pretences; and, when in, began to sow their bad seed. Before of old ordained - Οἱ παλαι προγεγραμμενοι Such as were long ago proscribed, and condemned in the most public manner; this is the import of the word προγραφειν in this place, and there are many examples of this use of it in the Greek writers. See Kypke. To this condemnation - To a similar punishment to that... read more