You shall not wrong a stranger or oppress him, for you were strangers in the land of Egypt. (Exodus 22:21)
The literal commandment is that we should not oppress strangers.
Messiah implicitly affirmed this commandment when He spoke about the Law:
"Do not think that I came to abolish the Law or the Prophets; I did not come to abolish but to fulfill. For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass from the Law until all is accomplished. Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven. (Matthew 5:17-19)
He also affirms this commandment in another way:
Then the King will say to those on His right, 'Come, you who are blessed of My Father, inherit the kingdom prepared for you from the foundation of the world. For I was hungry, and you gave Me something to eat; I was thirsty, and you gave Me something to drink; I was a stranger, and you invited Me in; naked, and you clothed Me; I was sick, and you visited Me; I was in prison, and you came to Me.' (Matthew 25:34)
Messiah teaches the importance of kindness to strangers.
The commandment "do not oppress the stranger" pictures Messiah in that, as sinners, we were all estranged from Him (Ephesians 2:12). He has authority over all things (Matthew 28:18) and has great power (Ephesians 1:20-21). It is entirely within His ability to call twelve legions of angels (Matthew 26:53) and harass or destroy those who opposed Him.
Instead He showed His mercy and grace and did not oppress those who were strangers to Him.
Messiah fulfilled this commandment by not oppressing strangers but instead treated them with kindness.
One example is found in His healing of a Canaanite woman's daughter. (Matthew 15:22-28)
There are at least two variations on traditional understanding and observance of this commandment:
The first way to understand this is "do not oppress the convert to Judaism". This approach takes the Hebrew word ger and translates it as "convert" instead of "stranger". Just as a person must not embarrass a native-born Jew, so too we must not oppress converts... even with words.
The second is that the commandment means "do not oppress the weak". This approach considers the next verse (Exodus 22:22- You shall not afflict any widow or orphan) and groups the stranger, the widow, and the orphan into a single group of those who have no authority or power within the ancient Israelite world... i.e. the weak.
Whether we understand this verse to refer to "the weak", "the convert", or "the stranger", we are able to fulfill this commandment today and should strive to be like the Messiah: He did not oppress the weak and neither should we.