死心塌地 They Have Given Up Hope
內中忽跳出一個小妖，告道：「大王，他們見堵了門，攻打不開，死心塌地，捨了唐僧，將假人頭弄做個墳墓。今日哭一日，明日再哭一日，後日復了三，好道回去。内中忽跳出一个小妖，告道：「大王，他们见堵了门，攻打不开，死心塌地，舍了唐僧，将假人头弄做个坟墓。今日哭一日，明日再哭一日，后日复了三，好道回去。
逐句解 Line by line
From among them a little fiend suddenly jumped out and made his report: "Great King, seeing the gate blocked and finding they could not batter it open, they have given it up as hopeless, abandoned the Tang Monk and made a grave out of the false head.
死心塌地, heart dead and feet flat on the ground, is still the ordinary phrase for having resigned oneself to something completely. The report is accurate about everything except the abandonment, and the fiends have no way to know that the pilgrims have not given up at all.
Today they weep for a day, tomorrow they weep another day, the day after they make it three, and then they will surely go home.
The little fiend has done the arithmetic of mourning. Three days is the shape of the first stage of a funeral observance, and he is predicting when the guests will leave — which is the coolest, most administrative thing anybody says in the chapter.
The fiend giving this report is a good analyst. He has read the enemy's behaviour correctly, understood the ritual timetable, and drawn a sound conclusion about when the pressure will lift. He is wrong only because he is missing one fact.
The phrase about the heart being dead and the feet flat on the ground has softened over the centuries. It now often means single-minded devotion — set on something and not to be shifted. Here it still has its older, bleaker sense: they have stopped hoping.