"A soul, when it sins" (Leviticus 4:2) - the children of Israel bring a sin-offering, but the nations do not bring a sin-offering. And it need not be said concerning the commandments that the descendants of Noah were not commanded; but even concerning the commandments that the descendants of Noah were commanded, the descendants of Noah do not bring a sin-offering for them. "The children of Israel" - I have only the children of Israel; from where to include the converts and the freed slaves? Scripture says "a soul, when it sins."
Who Brings a Sin-Offering Israel, Converts, and Freed Slaves
Yalkut Shimoni on Torah 464:4
נֶפֶשׁ כִּי תֶחֱטָא, בְּנֵי יִשְׂרָאֵל מְבִיאִין חַטָּאת וְאֵין הַגּוֹיִים מְבִיאִין חַטָּאת וְאֵין צָרִיךְ לוֹמַר מִצְווֹת שֶׁלֹּא נִצְטַוּוּ עֲלֵיהֶם בְּנֵי נֹחַ אֶלָּא אַף מִצְווֹת שֶׁנִּצְטַוּוּ עֲלֵיהֶם בְּנֵי נֹחַ אֵין מְבִיאִין עֲלֵיהֶם בְּנֵי נֹחַ חַטָּאת בְּנֵי יִשְׂרָאֵל, אֵין לִי אֶלָּא בְּנֵי יִשְׂרָאֵל, מִנַּיִן לְרַבּוֹת אֶת הַגֵּרִים וְהָעֲבָדִים הַמְשֻׁחְרָרִים תַּלְמוּד לוֹמַר "נֶפֶשׁ כִּי תֶחֱטָא".