"Be hospitable to one another without complaint." (NAS)
"Be hospitable to one another without grumbling." (KJV)
The word translated "be hospitable" is " philoxenos" -- simply, "hospitable, generous to guests".
The word translated "complaint" is "goggusmos" -- "a murmur, murmuring, muttering; a secret debate; a secret displeasure not openly avowed"
In other words, you're called to be hospitable without being cranky about it.
Lest hospitality seem a trivial, Martha Stewarty thing beneath the believer's notice, take a look at these studies and commentaries:
This is just a starter. Hospitality from a Scriptural standpoint is not the same as entertaining. It is recognizing God in others, and offering to them what we would offer to Our Lord -- a welcome, a meeting of the needs for food and shelter, a place of rest and refreshment.
How hospitable are we being when we deny our own offspring the safety of our wombs? If we refuse to love our own children, sheltered in our bodies, how can we claim to love our brothers and sisters who seek refuge in our homes?
Likewise we are called upon to offer hospitality to the troubled pregnant woman, to see to it that she has her needs met, so that she in turn can offer the hospitality of her love to her unborn child.