背心縛人 The Waistcoats Bind Them
那獃子莫想肯聽，對唐僧笑道：「師父啊，我自為人，也穿了幾件背心，不曾見這等納錦的。你不穿，且待老豬穿一穿，試試新，晤晤脊背。等師兄來，脫了還他走路。」沙僧道：「既如此說，我也穿一件兒。」兩個齊脫了上蓋直裰，將背心套上。才緊帶子，不知怎麼立站不穩，撲的一跌。原來這背心兒賽過綁縛手，霎時間，把他兩個背剪手貼心綑了。慌得個三藏跌足報怨，急忙來解，那裡便解得開。三個人在那裡吆喝之聲不絕，卻早驚動了魔頭。那呆子莫想肯听，对唐僧笑道：「师父啊，我自为人，也穿了几件背心，不曾见这等纳锦的。你不穿，且待老猪穿一穿，试试新，晤晤脊背。等师兄来，脱了还他走路。」沙僧道：「既如此说，我也穿一件儿。」两个齐脱了上盖直裰，将背心套上。才紧带子，不知怎么立站不稳，扑的一跌。原来这背心儿赛过绑缚手，霎时间，把他两个背剪手贴心捆了。慌得个三藏跌足报怨，急忙来解，那里便解得开。三个人在那里吆喝之声不绝，却早惊动了魔头。
逐句解 Line by line
The idiot had no intention whatever of listening. He laughed and said to the Tang Monk: "Master, in all my life I have worn a few waistcoats, but I have never seen quilted brocade like this.
莫想肯聽 — not to be thought of, that he would listen. 我自為人 takes 為 as the verb wéi, to be or to become: since I have been a person, that is, in all my life. Coming from a pig-headed immortal who spent an age as a marshal of Heaven, that is a phrase with more history in it than he means to put there.
If you will not wear one, let Old Hog put one on a while — try it new, and give my back a warming.
晤晤脊背 is to warm the back. Watch the request shrink by stages: keep them, then wear one, then wear one for a moment, then just try it on. Every concession makes the next one smaller and none of them gives anything up.
When elder brother comes, I will take it off, give it back, and we go on."
還 is huán, to give it back, matching the master's order in the passage before. He concedes the principle in full and does the thing anyway.
Sha Monk said: "If you put it that way, I will wear one too."
一件兒 takes the little er ending. This is Sha Monk's only line of quoted speech in the entire chapter — earlier he simply assented and said nothing. He breaks a chapter's silence to agree to the one thing he should have refused, and it costs him.
The two of them stripped off their outer gowns together and pulled the waistcoats on.
將 is the jiāng that takes hold of the object. 齊脫了 — they do it in unison, which is how the trap takes both of them at once.
They had barely tightened the ties when, somehow, they could not keep their footing, and down they went with a thump.
撲的一跌 — 撲 is the sound of the fall itself, a thump. 不知怎麼, somehow, leaves the cause unstated for one more sentence, which keeps the reader down at the level of the two victims instead of above them.
For these waistcoats were better than any binding-rope: in an instant they had the pair of them pinioned, arms twisted back and drawn tight against the chest.
賽過 is sài, to surpass, to beat. 綁縛手 is a cord for tying. 背剪手 is to have the arms forced back behind you; 貼心 draws them in tight against the body. 霎時間 takes 間 as jiān. The description is of a professional job of binding, done by a garment.
Tripitaka was thrown into such a fright that he stamped and lamented, and rushed to untie them — but how were they to be got undone?
慌得 takes 得 as the light de of how it turned out; 解得開 takes the second 得 as dé, could manage to — so the same character carries two readings inside one segment. 那裡便解得開 is rhetorical, so 那 reads nǎ.
The three of them kept up such a shouting there that it had already roused the fiend.
在那裡 is pointing here — over there — so 那 reads nà. 驚動了魔頭 names the fiend for the first time and closes the passage on him. That is the second half of the chapter title walking in: 神昏心動遇魔頭, the spirit darkened, the heart stirred, and they meet a fiend.
The waistcoats are a snare and nothing else — no fight, no spell to counter, no moment in which resistance was possible. Two of the three are taken by putting on a coat.
The trap is exactly proportioned to the fault. What catches them is wanting to be warm; the thing that binds them is the garment itself; and it binds them at the moment they fasten it, so the victim does the work. A fiend who wanted to make a point about desire could not have built it better.
Tripitaka is left free, and useless. He is outside the snare only because he refused the coat, and the noise he makes trying to help is what brings the fiend down on all of them.