Shama-il Tirmidhi Chapter 032, Hadith Number 003 (209).

Ibn Umar radiyallahu anhu says, Rasoolullah sallallahu alaihe wasallam said, ‘Three things should not be refused: pillow; fragrance (itr-oil); and milk.

Commentary
These things are mentioned because it is not a burden upon the one who gives these presents and by refusing, one may at times offend the giver. All these things are included in those which are simple and does not burden the one that presents it. By pillow, some ulama say it means presenting a pillow, as it does not burden a person. Some ulama say that it is just for one’s use while sitting, lying, sleeping, leaning, etc.