The Talmud Makkot 16a records the following exchange:
א"ר יוחנן אין לנו אלא זאת ועוד אחרת
א"ל ר' אלעזר היכא א"ל לכי תשכח נפק דק ואשכח
R' Yoḥanan said: [There are two mitzvot on this matter:] This one and another one.
R' Elazar said to R"Y: Which is that other mitzvah?
R"Y said to him: Find out for yourself!
R"E went out, examined the matter, and discovered the answer.
Is this a teaching that one must always check things out for oneself in matters of Torah, if one is capable, and not take anybody's word for it?