Xenia plays a very important role in both the Iliad and the Odyssey. The idea of obligations running in both directions makes it a much richer concept than simple “hospitality.”
These obligations seemed to be very important to the culture at the time. So much so that it was considered the domain of Zeus (Zeus Xenios) to protect strangers seeking shelter. There are plenty of examples in myth of people breaking the sanctity of xenia and receiving divine punishment for it.
Xenia was such a powerful social norm that for a warrior, in the heat of battle, is perfectly fine to temporarily be nude, exchange your finest armour for a lower grade one, and still be happy about it.
See also their translator's note to their translation