Yet the Lord testified against Israel. — Rather, And Jehovah adjured Israel... The verb means here, gave solemn warning, or charge. In 2 Kings 17:15 it is repeated, with a cognate noun as object: “His testimonies which he testified against them;” or, his charges (i.e., precepts) which he had given them.
By all the prophets, and by all the seers. — The Hebrew text is, by the hand of all his prophets — namely, every seer. One or two MSS. and the Targum have prophet, instead of his prophets. The Syriac has “by the hand of all his servants the prophets, and all the seers.” The Vulg. and Arabic also have both nouns plural. Seers were such persons as, without belonging to the prophetic order, came forward in times of emergency upon a sudden Divine impulse. Thenius thinks Israel and Judah are mentioned together because the reference is to the time before the partition of the kingdom; more probably, because both apostatised, and prophets were sent to both.
And which I sent — i.e., the law which I sent. But — as according to later Jewish ideas, the prophets did not bring the Law, but only interpreted it — it seems better to understand with the Vulg. (“et sicut misi”) “and according to all that I sent to you (i.e., enjoined upon you) by my servants the prophets.”