פּירוש אויף דברים 17:11

ימין ושמאל [THOU SHALT NOT DEPART FROM THE WORD WHICH THEY SHALL TELL THEE] TO THE RIGHT NOR TO THE LEFT, even if he (the judge) tells you about what appears to you to be right that it is left, or about what appears to you to be left that it is right, you have to obey him; how much the more is this so if actually he tells you about what is evidently right that it is right and about what is left that it is left (cf. Sifrei Devarim 154:5).

THOU SHALT NOT DEPART FROM THE WORD WHICH THEY SHALL TELL THEE, TO THE RIGHT NOR TO THE LEFT. “Even if he [the judge of the Great Sanhedrin] tells you of the right that it is the left, or about the left that it is the right [you must obey him].” This is Rashi’s language. The purport thereof is that even if you think in your heart that they are mistaken, and the matter is simple in your eyes just as you know [the difference] between your right hand and your left hand, you must still do as they command you. You are not to say: “How can I [permit myself to] eat this real forbidden fat, or execute this innocent man;” instead you are to say, “The Lord Who enjoined the commandments commanded that I perform all His commandments in accordance with all that they, who stand before Him in the place that He shall choose, teach me to do. He gave me the Torah as taught by them, even if they were to err.” Such was the case of Rabbi Yehoshua and Rabban Gamaliel [Rabbi Yehoshua being instructed by Rabban Gamaliel to come before him with his walking stick] on the Day of Atonement that occurred according to his reckoning.⁹⁰Following the destruction of the Second Temple, the Sanhedrin was re-established in Jabneh under the presidency of Rabban Yochanan ben Zaccai (see above, Note 19). It happened that his successor Rabban Gamaliel, once accepted the testimony of two witnesses with regard to proclaiming the New Moon. Rabbi Yehoshua held that their evidence was invalid, and that the New Moon should be proclaimed a day later. Since the month was Tishri, the Day of Atonement [i.e., the tenth of Tishri] would fall a day later according to Rabbi Yehoshua than according to the reckoning of Rabban Gamaliel. When Rabbi Yehoshua refused to accept the opinion of his colleague, who, by virtue of his presidency of the Sanhedrin, had the authority to make the binding decision, Rabban Gamaliel sent to him, “I order you to come to me carrying your walking stick and your money on the day you reckon to be the Day of Atonement. The order caused Rabbi Yehoshua personal anguish because carrying is forbidden on the Day of Atonement. The affair ended with Rabbi Yehoshua obeying Rabban Gamaliel’s command. When Rabbi Yehoshua arrived, “Rabban Gamaliel stood up and kissed him on the head and said to him; ‘Come in peace, my master and my disciple’ — ‘my master’ in wisdom, and ‘my disciple’ because you accepted my words” (Rosh Hashanah 25a).
Now the need for this commandment is very great, for the Torah was given to us in written form and it is known that not all opinions concur on newly arising matters. Disagreements would thus increase and the one Torah would become many Torahs. Scripture, therefore, defined the law that we are to obey the Great Court that stands before G-d in the place that He chose in whatever they tell us with respect to the interpretation of the Torah, whether they received its interpretation by means of witness from witness until Moses [who heard it] from the mouth of the Almighty, or whether they said so based on the implication [of the written words] of the Torah or its intent. For it was subject to their judgment that He gave them the Torah even if it [the judgment] appears to you to exchange right for left. And surely you are obligated to think that they say “right” what is truly right, because G-d’s spirit is upon the ministers of His Sanctuary,⁹¹Ezekiel 45:4. and He forsaketh not His saints; they are preserved forever⁹²Psalms 37:28. from error and stumbling. In the language of the Sifre:⁹³Sifre, Shoftim 154. “Even if they show you before your own eyes that right is left and that left is right — obey them!”

according to whatever teaching they direct you concerning the difficult matter.