"precept on precept, precept on precept; line on line, line on line" (28:10). What does it mean?

The chapter doesn't explain the words, so start with what it says. In Hebrew they are short words, each pair said twice: tsav latsav, tsav latsav, qav laqav, qav laqav, ze'eir sham, ze'eir sham (tap precept). They follow the questions of 28:9, "Whom will he teach knowledge? To whom will he explain the message?" (28:9), and the chapter doesn't say who asks them or whose words 28:10 are. Then the same words come back, and this time the chapter says what they are: "Therefore the LORD’s word will be to them precept on precept, precept on precept; line on line, line on line; here a little, there a little; that they may go, fall backward, be broken, be snared, and be taken" (28:13). The verse just before tells of those to whom he had said, "This is the resting place. Give rest to the weary", and who "would not hear" (28:12). So in this chapter the words stand in a warning. These notes don't say more than the verses do.