Isaiah 8:20

To the law, and to the testimony,.... Kimchi takes this to be an oath, "by the law, and by the testimony", it is so and so; but Aben Ezra observes there is no instance of this kind in Scripture; it is a direction of Christ's to his disciples, to attend to the writings of Moses and the prophets, to search the Scriptures, as in John 5:39 and particularly what is before said in this prophecy concerning himself, the same is meant as on Isaiah 8:16.

if they speak not according to this word; this sure word of prophecy, to which men do well to take heed, as to a light shining in a dark place, it being the rule of faith and practice, a lamp to the feet, and a light to the path:

[it is] because [there is] no light in them; that is, in them that speak not according to it, meaning the Scribes and Pharisees; who, rejecting the written word, set up the traditions of the elders above it, and taught the people to walk according to them; and so were, as our Lord says, "blind leaders of the blind", Matthew 15:14 or the words may be read, "if not"; if they will not regard the Scriptures, and the evangelical doctrine in them, and the testimony they give concerning Christ; "let them speak according to this word"; or instruction, and counsel, they have from the Scribes and Pharisees: "in which there is no light" b; but the darkness of ignorance, infidelity, superstition, and will worship; or "no morning"; but a night of Jewish darkness, even though the sun of righteousness was risen, and the dayspring from on high had visited the earth; yet they had received no light and knowledge from him, which was their condemnation, John 1:4 John 3:19 or thus, "to the law, and to the testimony, though they may say after this manner, there is no light in it" c; in the law and testimony, preferring the traditions, decisions, and determinations of their doctors above it. Noldhius d renders the words thus, "seeing they speak not according to this word, certainly they shall have no morning"; that is, seeing the seducers and false teachers, in the preceding verse Isaiah 8:19, speak not according to the word of God, and testimony of Jesus, they shall have no morning of light and joy, of grace and comfort, or any spiritual felicity; Christ will be no morning to them, but they will continue in their dark, benighted, and miserable condition, described in the following verse.

b אם לא יאמרו "sin minus, dicant secundum verbum istud, cui mon est aurora", Piscator. So Sanctius. c "Licet ipsi dicent, in verbis legis, nihil lucis esse", Oleaster in Bootius. d Ebr. Part. Concord. p. 374. No. 1302.