John Gill Commentary Leviticus 19:34

"The stranger that sojourneth with you shall be unto you as the home-born among you, and thou shalt love him as thyself; for ye were sojourners in the land of Egypt: I am Jehovah your God." — Leviticus 19:34 (ASV)

[But] a stranger that dwells with you shall be unto you as
one born among you

Especially if a proselyte of righteousness; for then he enjoyed the same privileges, civil and religious, the Israelites did, for there was one law for them both, (Exodus 12:49).

and you shall love him as yourself ;

and show it by doing all the good things for him they would have done for themselves in like circumstances:

for you were strangers in the land of Egypt :

and therefore knew what hardships such were exposed to; and it became them to put on bowels of compassion, and show pity to those in a like condition, and particularly consider, as Jarchi suggests, that they were idolaters there also, and therefore ought not to upbraid strangers with their former idolatry:

I [am] the Lord your God ;

who showed kindness to them when strangers in Egypt, and had brought them out of that land, and therefore ought to obey his commands, and particularly in this instance.