借辟火罩 Borrowing the Fire-Shield
快些拿來使使，即刻返上。」天王道：「你差了。既是歹人放火，只該借水救他，如何要辟火罩？」行者道：「你那裡曉得就裡。借水救之，卻燒不起來，倒相應了他；只是借此罩，護住了唐僧無傷，其餘管他，盡他燒去。快些，快些，此時恐已無及，莫誤了我下邊幹事。」那天王笑道：「這猴子還是這等起不善之心，只顧了自家，就不管別人。」行者道：「快著，快著，莫要調嘴，害了大事。」那天王不敢不借，遂將罩兒遞與行者。快些拿来使使，即刻返上。」天王道：「你差了。既是歹人放火，只该借水救他，如何要辟火罩？」行者道：「你那里晓得就里。借水救之，却烧不起来，倒相应了他；只是借此罩，护住了唐僧无伤，其余管他，尽他烧去。快些，快些，此时恐已无及，莫误了我下边干事。」那天王笑道：「这猴子还是这等起不善之心，只顾了自家，就不管别人。」行者道：「快着，快着，莫要调嘴，害了大事。」那天王不敢不借，遂将罩儿递与行者。
逐句解 Line by line
"Quick, hand it over and let me use it; I will return it this instant." The Deva King said, "You are mistaken.
你差了: 差 is chà, "in error" — the same reading and very nearly the same rebuke that a young monk delivered to his abbot an hour ago. Heaven and the monastery speak the same idiom. And note the promise Wukong has just made: 即刻返上, "I will send it straight back up." Remember it. He is the only person in this chapter who keeps such a promise.
"If villains are setting a fire, you should borrow water to save him. What do you want with a fire-shield?"
The Deva King raises the moral objection without knowing that is what he is doing. Water saves; a shield saves only whatever stands beneath it. He assumes Wukong means to put the fire out. Nobody in Heaven has yet understood what has actually been asked for.
The Pilgrim said, "How should you know the inside of it? Borrow water, save him, and the fire never takes hold — which would only suit them.
那裡 is nǎ, "how would you." 就裡 is the inner truth of a matter, what is really going on. 相應 is xiāng yìng — "it would suit them," meaning it would spare them the loss they had prepared for other people. The reasoning is impeccable, and its unstated premise is that they deserve to lose everything.
"Lend me this shield instead: it will guard the Tang monk from harm, and as for the rest, let them look to it; let the whole of it burn."
其餘管他 ("as for the rest, let him mind it") and 盡他燒去 ("let it burn to the end"; 盡 is always jìn). Two clauses, and two hundred and thirty men lose their house. The verb Wukong wants is not extinguish but enclose.
"Quick, quick — I fear it is already too late. Do not make me miss my business down below."
幹事 is "the business to be done." He is being impatient with a god because a fire he intends to feed may burn itself out before he can get down there to feed it.
The Deva King laughed. "This monkey is still the same: he raises an unkind heart, thinks only of his own, and cares nothing for anyone else."
The Deva King's laugh is the novel's verdict, and it is delivered by a bystander with no stake in the matter: 起不善之心 ("raises a heart that is not good"), 只顧了自家，就不管別人 ("looks after his own and lets others be"). It is said lightly, the way old friends tease. It is exactly true. And the shield is lent anyway.
The Pilgrim said, "Hurry, hurry. Don't stand wagging your tongue and ruin a great matter."
快著，快著 — the sentence-final modal 著, read zhe, which turns a word into a nudge. 調嘴 is tiáo zuǐ, to wag the tongue, to bandy words. He is telling a Deva King of Heaven to stop talking.
The Deva King dared not refuse to lend it, and handed the shield over to the Pilgrim.
不敢不借, "dared not not lend it." That double negative is the whole of Heaven's position with respect to this creature. Nobody up here has forgotten chapter five either.
This is the most morally exposed conversation in the chapter, and it is conducted entirely in the register of a favour between old acquaintances. The Deva King, hearing of a fire, proposes water. Wukong explains, patiently, that water would ruin everything: 卻燒不起來，倒相應了他 — the fire would fail to catch, and that would suit the arsonists. He wants a shield not because a shield saves more but because a shield saves less. It saves precisely one hall, one horse and one sleeping man, and lets everything else go.
And Heaven lends it. 那天王不敢不借 — "the Deva King dared not not lend it." Before handing it over he pronounces the verdict the narrator never pronounces: 這猴子還是這等起不善之心，只顧了自家，就不管別人. Still the same creature, raising an unkind heart, minding his own and nobody else's. He says it laughing, the way a friend teases a friend. Before long Guanyin herself will say something very like it, and she will not be laughing. Wú Chéng'ēn has arranged the whole episode so that the gods of the celestial bureaucracy are implicated in what follows: they saw what he intended, they named it correctly, and they gave him the equipment.