A few quotes from the Rabbi on 'Love of Israel'
in which he teaches to share bread with those who do not recite the blessings, there being a commandment to welcome guests.
His Honor was asked by a friend, a religious person who has well-bred secular friends whom he hosts at home and to whom he serves food at his table, such as meat and wine, and offers them all manner of things, whether this does not involve a transgression, since it is forbidden to share bread with one who does not recite the blessing.
Maran [Our Master], of blessed memory…did not write this in the sense of prohibition but rather as a warning, meaning stringency… since he is fulfilling the commandment of hospitality he is not transgressing "do not place a stumbling-block before the blind", and whether he recites the blessing or doesn't, he should serve him.
Every instance of hospitality has a reason and is an inherent commandment, whether it be receiving guests, brotherly love, granting a favor, domestic harmony, forestalling a threat or obtaining a favor, or unexpected visits that are difficult to send off empty-handed, and it is also a great sin to offend their dignity…
If so, since in each sense there is an aspect of a major or minor commandment, and it is very problematic to embarrass and very problematic to rebuke, and not everyone knows how to rebuke, silence is therefore called for, and amity is best, so that one should receive every person gracefully and provide them with food and drink to their good health, and the Almighty will determine his reward.
Otzar HaMichtavim, Chapter 3, letter A 815, p. 182. Published by Otzrot HaMaghreb, Bnei Issachar Institute, Jerusalem, 1988