וְגֵר לֹא תוֹנֶה וְלֹא תִלְחָצֶנּוּ The first portion says, "And you shall not hurt the feelings of a stranger" (Shemoth 22:20). Rabbenu Bahya writes that this refers to causing harm to him verbally, as is explained by Rashi. The next portion says, "you shall not take advantage of him". This comes to tell us that one may not negatively affect him physically, such as by stealing from him.
In fact, this is just one of many instances where the Torah speaks about a stranger or Ger (proselyte), and how he must be treated fairly and appropriately. The word "Ger" implies a lone berry at the end of a long branch. A Ger is like this berry, alone with no family to support or protect him. We can imagine that he is particularly vulnerable emotionally as well as physically. Human inclination is to treat such a person disrespectfully and to take advantage of him.
The Torah warns us we must be very careful in our behavior towards a stranger. We would be greatly mistaken if we thought that there was no one to take up his cause. The Holy One Blessed be He will take up his cause. Just like G-d took up our cause when we were strangers in the land of Egypt, so too He would take up the cause of the stranger in our midst if he were treated unfairly.
This is just another example of how the Torah ensures that the Jewish people adhere to principles that are above the norm of the nations around us.
(See Rabbenu Bahya on the Torah, Mishpatim 22:20)
Parasha, Mishpatim, treating strangers