"From all the commandments of the LORD" (Leviticus 4:27) - and not the commandment of a king, and not the commandment of a court. The commandments stated regarding the anointed priest, the commandments stated regarding the congregation, the commandments stated regarding the prince, they are the commandments stated here. "From the commandments of the LORD" - and not all the commandments of the LORD, excluding the hearing of a voice [oath of testimony], the utterance of the lips [rash oath], and the defilement of the Sanctuary and its holy things. "Which may not be done" - this teaches that he brings an offering for an inadvertent act. "And he becomes guilty" - this teaches that he brings a suspended guilt offering. "Or if his sin be made known to him" (Leviticus 4:28) - and not that others told him; one might think this is so even though he does not deny it; the verse teaches "his sin which he has sinned therein."
The Commandments of the LORD and Not the Decrees of a King
Yalkut Shimoni on Torah 469:36
מִכָּל מִצְוֹת ה', וְלֹא מִצְוַת הַמֶּלֶךְ, וְלֹא מִצְוַת בֵּית דִּין. מִצְווֹת הָאֲמוּרִים בְּמָשִׁיחַ מִצְווֹת הָאֲמוּרִים בְּעֵדָה מִצְווֹת הָאֲמוּרִין בְּנָשִׂיא הֵן מִצְווֹת הָאֲמוּרִים כָּאן. מִמִּצְוֹת ה', וְלֹא כָּל מִצְווֹת ה', פְּרָט לִשְׁמִיעַת קוֹל וּלְבִטּוּי שְׂפָתַיִם וּלְטֻמְאַת מִקְדָּשׁ וְקָדָשָׁיו. אֲשֶׁר לֹא תֵעָשֶׂינָה, מְלַמֵּד שֶׁהוּא מֵבִיא עַל שִׁגְגַת מַעֲשֶׂה. וְאָשֵׁם, מְלַמֵּד שֶׁמֵּבִיא אָשָׁם תָּלוּי. (ויקרא ד כח) אוֹ הוֹדַע אֵלָיו, וְלֹא שֶׁאָמְרוּ אֲחֵרִים, יָכוֹל אַף עַל פִּי שֶׁאֵינוֹ מַכְחִישׁ, תַּלְמוּד לוֹמַר ("חַטָּאתוֹ אֲשֶׁר חָטָא בָּהּ").