Sacred texts from many faiths state the shraed value of welcoming the stranger. 

Baha’i Tradition (from Abdu'l-Baha, Selections from the Writings of Abdu'l-Baha)

One amongst His Teachings is this, that love and good faith must so dominate the human heart that men will regard the stranger as a familiar friend, the malefactor as one of their own, the alien even as a loved one, the enemy as a companion dear and close.

Christian Tradition (from Matthew 25:35)

“For I was hungry and you gave me food, I was thirsty and you gave me something to drink, I was a stranger and you welcomed me, I was naked and you gave me clothing, I was sick and you took care of me, I was in prison and you visited me.” Then the righteous will answer him, “Lord, when was it that we saw you hungry and gave you food, or thirsty and gave you something to drink? And when was it that we saw you a stranger and welcomed you, or naked and gave you clothing? And when was it that we saw you sick or in prison and visited you?” And the king will answer them, “Truly I tell you, just as you did it to one of the least of these who are members of my family, you did it to me.”

Hindu Tradition (from Taitiriya Upanishad 1.11.2)

Let a person never turn away a stranger from his house, that is the rule.  Therefore a man should, by all means, acquire much food, for good people say to the stranger: ‘There is enough food for you.’”

Jewish Tradition (from Deuteronomy 10:17)

For the LORD your G-d is G-d supreme and Lord supreme, the great, the mighty, and the awesome G-d, who shows no favor and takes no bribe, but upholds the cause of the fatherless and the widow, and befriends the stranger, providing him with food and clothing. You too must befriend the stranger, for you were strangers in the land of Egypt.

Muslim Tradition (from Surah 4:36)

Do good unto your parents, and near of kin, and unto orphans, and the needy, and the neighbor from among your own people, and the neighbor who is a stranger, and the friend by your side, the wayfarer, and your servants.

Secular Humanism (from the writings of Pablo Neruda)

To feel the intimacy of brothers is a marvelous thing in life. To feel the love of people whom we love is a fire that feeds our life. But to feel the affection that comes from those whom we do not know, from those unknown to us, who are watching over our sleep and solitude, over our dangers and our weaknesses -- that is something still greater and more beautiful because it widens out the boundaries of our being, and unites all living things.

Sikh Tradition (from Guru Granth Sahib)

None is our enemy, none is stranger to us, we are in accord with one and all.

Native American Tradition (from Chief Tecumseh, Shawnee Nation)

Always give a word or a sign of salute when meeting a passing friend, even a stranger, when in a lonely place.  Show respect to all people and grovel to none.