isaiah 45:19 I have not spoken in secret, in a dark place of the earth: I said not unto the seed of Jacob, Seek ye me in vain: I the LORD speak righteousness, I declare things that are right. - Free Bible Online

      19. not . . . secret--not like the heathen oracles which gave their responses from dark caverns, with studied obscurity (Isa 48:16). Christ plainly quotes these words, thereby identifying Himself with Jehovah (Joh 18:20).
      I said not . . . Seek . . . in vain--When I commanded you to seek Me (Jehovah did so, Isa 45:11, "Ask Me," &c.), it was not in order that ye might be sent empty away (De 32:47). Especially in Israel's time of trial, God's interposition, in behalf of Zion hereafter, is expressly stated as about to be the answer to prayer (Isa 62:6, 7-10; Ps 102:13-17, 19-21). So in the case of all believers, the spiritual Israel.
      righteousness--that which is veracious: not in the equivocal terms of heathen responses, fitly symbolized by the "dark places" from which they were uttered.
      right--true (see on Isa 41:26).

JFB.