John Gill Commentary Numbers 15:29

"Ye shall have one law for him that doeth aught unwittingly, for him that is home-born among the children of Israel, and for the stranger that sojourneth among them." — Numbers 15:29 (ASV)

You shall have one law for him that sinneth through ignorance ,
&c.] Which enjoins a she goat for a sin offering for such:

[both] for him that is born among the children of Israel, and for
the stranger that sojourns among them ;
both sinning through ignorance, the same sacrifice was offered for them, by which atonement was made, and through which their sin was forgiven; by whom are meant homeborn Israelites and proselytes of righteousness, who were under the same laws, and enjoyed the same privileges, as do now believing Jews and Gentiles.