Consider the following:
quote:
…and even on the view that precepts cannot nullify each other, that applies only to a Biblical [precept] with a Biblical [precept], or a Rabbinical [precept] with a Rabbinical [precept], but in the case of a Scriptural and Rabbinical [precept], the Rabbinical [one] comes and nullifies the Scriptural [one]. (b.Pesachim 115a).
quote:
A person must not say, “I will not keep the commandment of the elders because they are not from the Torah.” The Almighty says to such a person, “No, My son! Rather all that they decree upon you, observe! As it is written, According to the instruction which they teach you (Deuteronomy 17:11), Even I [HaShem] must obey their decree, as it is written, You will decree and He will fulfill it (Job 22:28).” (Pesikta Rabbati Par. 3).
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Even when they (the Rabbis) decide that left should be right or right left, when they are mistaken or misled in their judgment, they must be obeyed (b.Rosh Hashanah 25a).
quote:
Rava expounded: My son! Be careful concerning Rabbinical decrees even more than the Torah. Because the Torah contains requirements and prohibitions, while the Rabbinical decrees: Anyone who violates a Rabbinical decree is worthy of death (b.Eruvin 21b).