對頭又來 The Adversary Returns
那大仙說聲趕，縱起雲頭，往西一望，只見那和尚挑包策馬，正然走路。大仙低落雲頭，叫聲：「孫行者，往那裡走？還我人參樹來。」八戒聽見道：「罷了，對頭又來了。」行者道：「師父，且把善字兒包起，讓我們使些兇惡，一發結果了他，脫身去罷。」唐僧聞言，戰戰兢兢，未曾答應。那大仙说声赶，纵起云头，往西一望，只见那和尚挑包策马，正然走路。大仙低落云头，叫声：「孙行者，往那里走？还我人参树来。」八戒听见道：「罢了，对头又来了。」行者道：「师父，且把善字儿包起，让我们使些凶恶，一发结果了他，脱身去罢。」唐僧闻言，战战兢兢，未曾答应。
逐句解 Line by line
That Great Immortal gave the word to give chase, sprang up on a cloud-head, and looking away west saw that monk plodding along, whip in hand and horse before him, going on his way.
挑包策馬, tiāo bāo cè mǎ, shouldering the bundle and urging the horse along, is the party in its travelling formation. 正然走路, just then going along the road — the flat innocence of the phrase is the setup.
The Great Immortal brought his cloud down low and called out, "Sun the Pilgrim, where are you off to?
往那裡走, wǎng nǎ lǐ zǒu, "where do you think you're going?" — interrogative 那 as nǎ. The same four characters came out of Bajie's mouth at the locked gate on the first night; this time there is no disguise behind them.
"Give me back my ginseng tree!"
還我人參樹來, give me back my ginseng tree — 還 as huán, "to return," 參 as shēn. He asked for this once before and will keep asking; it is the demand that shapes the next chapter.
Bajie, hearing it, said, "It's all up—the enemy's come again."
對頭, duì tóu, is an adversary, the person set opposite you. 罷了, "that's that, we're done for."
The Pilgrim said, "Master, just wrap up the word 'mercy' for now; let us use a little ferocity, finish him off at one stroke, and be off."
And Wukong proposes murder, in a very careful sentence. 把善字兒包起 — "wrap up the word 善 and put it away" — is a remarkable image: goodness as a written character, folded into a parcel for the duration. 字兒 takes the diminutive suffix 兒, ér. 一發結果了他, yì fā jié guǒ le tā, finish him off at one go; 結果 as a verb means to make an end of somebody.
The Tang Monk, hearing this, trembled and shook and gave no answer.
戰戰兢兢, zhàn zhàn jīng jīng, trembling with fear, is still the everyday phrase for doing something in terror. 未曾答應, gave no answer — and the silence is a refusal. 應 is yìng.
The adversary catches them on an open road in daylight, with no disguise and no preliminaries. Bajie's 罷了，對頭又來了 — that's torn it, he's back — is the honest reaction of a party that has now spent two nights running and got nowhere.
Wukong's proposal is the darkest thing he says in the chapter, and the phrasing is what makes it land. Not "let me kill him" but 把善字兒包起: wrap up the word "goodness" and put it away for a bit. Mercy treated as a written character you can fold into a parcel and take out again afterwards.
Sanzang says nothing, and the nothing is the answer. He is shaking too hard to speak, but he does not give permission, and he never will; the refusal to sanction killing is the one position he holds without wavering through the entire novel, and it costs him a great deal here.