困於何所 Where Are They Penned
問及妖怪原由，行者把先請祖師、龜、蛇，後請大聖借太子，並彌勒收降之事，細陳了一遍。三藏聞言，謝之不盡，頂禮了諸天，道：「徒弟，這些神聖，困於何所？」行者道：「昨日日值功曹對老孫說，都在地窖之內。」叫：「八戒，我與你去解脫他等。」问及妖怪原由，行者把先请祖师、龟、蛇，后请大圣借太子，并弥勒收降之事，细陈了一遍。三藏闻言，谢之不尽，顶礼了诸天，道：「徒弟，这些神圣，困于何所？」行者道：「昨日日值功曹对老孙说，都在地窖之内。」叫：「八戒，我与你去解脱他等。」
逐句解 Line by line
When they asked how the fiend had come about, Pilgrim set out in detail how he had first asked the Patriarch for Tortoise and Snake, then asked the Great Sage for the loan of the prince, and how Maitreya had subdued him.
降 is xiáng, to subdue, in 收降 — the reading it took at the god of Wudang's own campaign, not the jiàng of coming down. 太子 is tài zǐ. The whole chapter is summarised here in one sentence with three clauses.
Tripitaka heard him and could not have done with thanking; he bowed to the heavens and said, "Disciple, where are all these holy beings penned?"
藏 is zàng. Tripitaka's first question on being freed is about the beings still imprisoned, which is the most characteristic thing he does in the chapter.
Pilgrim said, "Yesterday the Merit Star on duty for the day told Old Monkey they were all inside the cellar."
The Merit Star's information, given on a hilltop several scenes ago, is used here for the first time — and it is the only thing that scene produced besides the name of the Bodhisattva of Xuyi.
He called, "Eight Rules, come with me and set them free."
解脫 is the ordinary word for untying and also the Buddhist term for liberation, and the chapter lets it carry both at once.
Pilgrim's account of the chapter runs to three clauses, and it is the fourth time he has told the story — to the god of Wudang at twelve segments, to the Bodhisattva of Xuyi at four, and now to his own master in one sentence. Each telling has been shorter than the last.
What he includes this time is only the borrowing: first Tortoise and Snake, then the prince, then Maitreya. Every defeat has dropped out. The version a master gets is the version in which help was obtained.
Tripitaka asks after the star-gods before he asks anything else, and the question is the chapter's quiet correction of its own hero. Monkey has spent the chapter losing borrowed companies and moving on to borrow more; the first thing his master wants to know is where they are.