In Matthew 25:31-46, Christ tells us what we need do for salvation. One of these is "welcome the stranger". See also:

Exodus 22:21, "You must not mistreat or oppress foreigners in any way. Remember, you yourselves were once foreigners in the land of Egypt."

Exodus 23:9, "Do not oppress a foreigner; you yourselves know how it feels to be foreigners, because you were foreigners in Egypt."

Deuteronomy 10:19, "You shall also love the stranger, for you were strangers in the land of Egypt."

In the Talmud, a repeated admonition  is deemed particularly important. The Torah repeats it three times.

Jeremiah 22:3, "Thus says the Lord: Act with justice and righteousness, and deliver from the hand of the oppressor anyone who has been robbed. And do no wrong or violence to the alien, the orphan, and the widow, nor shed innocent blood in this place."

Running into the character limit, so I shall just mention that Ezekiel 47:21-23 tells Israel to treat foreigners as if they were native Israelites