Be not forgetful to entertain strangers, for thereby some have entertained angels unawares. (Hebrews 13:2 KJV).
The word "entertain" can also be translated as "show love to" (RSV), "show hospitality to" (TEV), "be friendly to" (JNT), and "welcome" (NJB). These actions were a moral obligation for every family in Israel. According to one Middle Eastern scholar,
"The hospitality of the Eastern peoples exceeds all their other virtues. While the greetings of peace from a visitor are received by the host of the house, the women immediately rush to take the shoes from his feet...and bring cold water to wash them. (After being offered a drink) and as a mark of genuine hospitality, a guest is asked as often as seven times to eat. The guest refuses by saying, "Thank you. I have just eaten. I am not hungry." But the host insists by holding on to his garment and urging him, saying, "By God and his Holy Scriptures, you must eat." This is the custom to which Jesus referred in the parable about compelling guests to attend." (My Neighbor Jesus 45)
There were times when a guest was not welcome and none of the members of the house would rise to meet him. George Lamsa tells of such an experience and the response of the rejected guest:
The guest's greetings of peace are returned to him in such a cold manner that he immediately understands that he is not welcome. At such discourtesy, the visitor then loosens the straps of his sandals and shakes the sand out. When this is done near the entrance of the house, it signified that the house has broken the sacred code of hospitality. The dust became a witness. The tired and dusty traveler will refuse to even quench his thirst in that house (MNJ 46).
But such occasions were quite rare. Because of Abraham's experience, they believed that every stranger potentially carried a divine message. To reject the stranger would also be a rejection of the Lord whose message he bore. The host would, by such an action, offend God and cut himself off from further opportunities to receive such important communications. Generally, Easterners were more willing to feed and shelter even their enemies rather than gain a reputation for being inhospitable.
Beloved Bridegroom Chapter 8