Musar על אבות 5:2

Behold, a man is obligated to guard all of the mitzvot in all of their fine details, doing so before any person, whoever it may be, and not be afraid or ashamed before him. Likewise, it is written: "I will also speak of Your testimonies before kings, and will not be ashamed" (Tehilim 119:46). And we also learned "be brazen as a leopard..." (Avot 5:2).