大般涅槃經義記 8.262

8.262

自下第二以人不取破其定有。「汝言有酪」牒上執辭，「何故賣人但取乳價不責酪直」就乳正徵。偏取乳價不責酪直，明知無酪。「賣草馬」下舉事類徵。

From here below is the second [point], using human non-procurement to refute its definitive existence. "You say there are curds" takes up the words of his grasping above; "Why does the seller only take the price of milk and not demand the price of curds?" directly interrogates with regard to milk. Procuring solely the price of milk and not demanding the price of curds clearly indicates that there are no curds. Below "Selling a mare...", he adduces a case to analogously interrogate.