His word that he had commanded, etc. "Commanded," i.e. given in charge to. Comp. Zechariah 1:6, My words and my statutes, which I commanded my servants the prophets." Zechariah continues, in language which illustrates the foregoing words of this verse, "Did they not take hold of [overtake] your fathers;" where the persons spoken of as "your fathers" are the same as those who are represented by the speaker of the elegy.
"In the days of old;" alluding, perhaps, to such passages as Deuteronomy 28:52, etc. The horn of thine adversaries. "Horn" has a twofold meaning—"strength" or "defence" (comp. Deuteronomy 28:3), and "honour" or "dignity".
The figure is too natural to need explanation.