If Imaam Ahmed (rahimahullah) received an invitation to a da’wat, be it a wedding or some other da’wat, then he would accept the invitation. If due to some excuse, he was unable to attend the da’wat, he would excuse himself from attending. However, if he attended a da’wat and had seen wrong taking place e.g. the food being served in silver or gold utensils or any other wrong, he would immediately wake up and leave the da’wat.
(Siyar A’laam min Nubalaa vol. 11 pg. 226)