In his commentary on 1 Timothy 6:10, Charles Ellicott wrote,
For the love of money is the root of all evil.—Some would water down this strong expression by translating the Greek words by “a root of all evil,” instead of “the root,” making this alteration on the ground of the article not being prefixed to the Greek word rendered “root.” This change, however, grammatically is unnecessary, as the article disappears before the predicate, in accordance with the well-known rule respecting subject and predicate.
The Greek text of 1 Timothy 6:10:
Ιʹ ῥίζα γὰρ πάντων τῶν κακῶν ἐστιν ἡ φιλαργυρία ἡς τινες ὀρεγόμενοι ἀπεπλανήθησαν ἀπὸ τῆς πίστεως καὶ ἑαυτοὺς περιέπειραν ὀδύναις πολλαῖς TR, 1550
To what “well-known [Greek] rule respecting subject and predicate” does Ellicott refer?
1 Ellicott, p. 211, 1 Tim. 6:10
A New Testament Commentary for English Readers. Vol. 3. Ed. Ellicott, Charles John. London: Cassell, 1884.