John Gill Bible Commentary

According to the sentence of the law which they shall teach thee,.... For they were not to make any new law, but to teach the law of God, and so far as their sense and opinion of things agreed with that law they were to be regarded: and according to the judgment which they shall tell thee, thou shalt do; what were law and justice, what were fit and right to be done, according to the will of God, which they should declare unto them, that was carefully to be done by them: thou shalt not decline from the sentence they shall show thee, to the right hand nor to the left; by setting up after, all their own judgments against theirs to whom they had applied for information and direction, which to have done would have been very insolent and affronting; they were not to depart from the determination they made of the case, on pretence of knowing better, nor even in any minute circumstance to deviate from it, but strictly and closely to keep unto it; though not to follow them so implicitly as to receive from them and embrace things the most absurd and unreasonable, as Jarchi suggests; who says, that their sense was to be abided by, even if they should say that the right hand is the left, and the left hand the right.