וְגֵ֥ר לֹא־תוֹנֶ֖ה וְלֹ֣א תִלְחָצֶ֑נּוּ כִּֽי־גֵרִ֥ים הֱיִיתֶ֖ם בְּאֶ֥רֶץ מִצְרָֽיִם׃
און אַ פֿרעמדן זאָלסטו ניט קריװדען, און זאָלסט אים ניט דריקן, װאָרום פֿרעמדע זײַט איר געװען אין לאַנד מִצרַיִם.
Rashi
וגר לא תונה — means, do not vex him with words (referring to the fact that he is a stranger); contrarier in old French Similar is, (Isaiah 49:26) “And I will feed them that vex thee (מוניך) with their own flesh”.
Bekhor Shor
1. YOU SHALL NOT OPRESS: since he does not know the matters of the land, it is an easy thing to oppress him.
Chizkuni
וגר לו תונה, “and you must not oppress a convert;” the reason why this verse follows that about converts serving both Hashem and their previous deities, is that G-d wishes to go on record that although He finds serving another deity as something repulsive, He does love converts and appreciates that they distanced themselves from their former religion.