Musnad Ahmed: Hadith 2726

Umar entered upon the Messenger of Allah (ﷺ), when he was lying on a reed mat that had left marks on his side, and he said: O Prophet of Allah, why don't you have furnishings that are more comfortable than this? He said: "What do I have to do with this world? The likeness of me and this world is that of a rider who travels on a summer day, then seeks shade beneath a tree for a while during the day, then he moves on and leaves it.”