“and you should act according to the matter which they will tell you” (Devarim 17,10)
It is a positive commandment to listen to the Great Beth Din to do whatever they command us in the ways of the Torah, whether permitted things or forbidden things, concerning purity or impurity, concerning who is guilty and who is innocent and about any matter which they see as strengthening or fixing our laws. About this it says “and you should act according to the matter which they will tell you”. There is no difference in this issue between things which they show you from their own opinions and things which they extract using one of the measures through which Torah is delved out, or things which they agree are secrets of the Torah, or any other issue which they consider to be so. In any case, we are obligated to listen to them.
Amongst the roots of the commandment: we are commanded through this commandment to strengthen the fulfilment of our law for if each person would fulfil the commandments of the Torah according to his own conception, each and every Jewish person could say “My opinion is that the truth of the matter is such and such” and this will result in catastrophe for the Torah will become many Torahs for each person will judge according to the inadequacy of his own understanding. However, now that we have been commanded to accept the opinion of the wise men of the Torah, there is one Torah for all of us and we cannot move from their opinion no matter what may be. And so, when we perform their commandments, we complete the commandments of G-d, and even if, G-d forbid, it happens sometimes that the Chachamim do not guide us to the truth, the sin falls on them and not on us.
This commandment applies at a time when there is a big Beth Din in Yerushalayim, to both men and women for everyone is commanded to do that which the Chachamim have taught us. Included in this commandment too is to listen and act at each and every time according to the commandment of the judge of those days; that is to say, according to the commandment of the biggest Chacham that we have amongst us at that time. And, as Chazal have explained from the verse “and to the judge who will be in those days” Yiftach in his generation was like Shmuel in his generation; that is to say, that it is incumbent upon us to listen to the voice of Yiftach in his generation in the same way that it is incumbent upon us to listen to Shmuel in his generation. One who does not listen to the advice of the people who are great in the wisdom of Torah of his generation according to all that they command, transgresses this positive commandment and his punishment is exceedingly great for this is the strong pillar upon which the Torah is supported, the matter is self explanatory to anyone with common sense.