Whom shall He teach knowledge? And whom shall He make to understand doctrine? Them that are weaned from the milk, and drawn from the breasts.
For precept must be upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little:
For with stammering lips and another tongue will He speak to this people, to whom He said, this is the rest wherewith ye may cause the weary to rest; and this is the refreshing: yet they would not hear.
But the word of the Lord was unto them precept upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little; that they might go, and fall backward, and be broken, and snared, and taken.
(Isaiah 28:9-13)
precept upon precept, because He will speak to that people with another tongue.
line upon line, in order that they fall backwards, be broken, snared and taken captive.
it doesn't seem to me in the context that 'precept upon precept, line upon line, here a little, and there a little' is a favorable thing.
it's a judgement.
it's because He told them of His Rest, but they would not hear it, nor give it to the weary.
i rather think we as humans tend to abuse that passage and treat it like it's something it really isn't -- and you may notice that verse 13 is very rarely quoted in full: people like to say 'precept on precept' to justify adding things one to another, but they don't like what the Bible says that situation is meant to result in, or to recognize the reason that situation came about.