Musnad Ahmad 30:506

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from al-Zuhri, from Ibn al-Musayyib and al-A'raj, from Abu Hurayrah, who said: "The worst of food is the food of the wedding feast, to which the rich are invited and the poor are left out. It is a right, and whoever abandons it has disobeyed." And Ma'mar would sometimes say: "And whoever does not answer the invitation has disobeyed Allah and His Messenger."