Albert Barnes on 1 Peter 4:9

Use hospitality one to another. On the duty of hospitality, Rom 12:13; Heb 13:2.

Without grudging. Greek, "without murmurs;" that is, without complaining of the hardship of doing it; of the time, and expense, and trouble required in doing it. The idea of grudging, in the common sense of that word--that is, of doing it unwillingly, or regretting the expense, and considering it as ill-bestowed, or as not producing an equivalent of any kind--is not exactly the idea here. It is that we are to do it without murmuring or complaining. It greatly enhances the value of hospitality, that it be done On our part with entire cheerfulness. One of the duties involved in it is to make a guest happy; and this can be done in no other way than by showing him that he is welcome.

(b) "hospitality" Heb 13:2,16 (+) "grudging" "murmuring"