פירוש על עבודה זרה 13:9

Section one of the baraita says that one should not go seeking lenient views. If someone asks a rabbi a question and the rabbi gives a stringent answer, one should not go out and seek a leniency. [We should note, that this does not mean the leniency is wrong in absolute terms. This very source is an interesting statement on the fact that there are often multiple “correct” answers in halakhah, but that in the end, one must be followed].
Section two says that if one asks two rabbis and one is strict and the other lenient, if one rabbi is greater than the other, then his opinion should be followed. If not, then the stricter opinion should be followed.
Joshua b. Korha says that only if the matter is from the Torah must the stricter opinion be followed. If it is from the rabbis, then one may be lenient. The halakhah accords with this opinion.