Hospitality is an important principle in Jewish and Christian ethics (1 Peter 4:9; see also Matthew 10:11; Acts 16:15; Titus 3:13; Philemon 1:22; 3 John 1:5–8). In the first century, travelers usually did not stay at inns.
some people have entertained angels without knowing it: See Genesis 18:2–15; Judges 13:2–23.