BT Tem 30b(15) :גבי ע׳ז ניחא ליה בניפחיה גבי שור הנסקל לא ניחא ליה בניפחיה‏ : in the case of suspicion of paganism he wants its full shape, in the case of the "stoned ox" he doesn't care about its full shape
See the entire entry for npaḥ, nepḥā n.m. volume