緊靠著身 The Bottle Grows With Him
他想道：「我把身子長一長，券破罷。」好大聖，捻著訣，念聲咒，叫：「長！」即長了丈數高下。那瓶緊靠著身，也就長起去。他把身子往下一小，那瓶兒也就小下來了。他想道：「我把身子长一长，券破罢。」好大圣，捻著诀，念声咒，叫：「长！」即长了丈数高下。那瓶紧靠着身，也就长起去。他把身子往下一小，那瓶儿也就小下来了。
逐句解 Line by line
He thought: "I will stretch myself a bit taller and split it open."
長 is zhǎng in both places here — to grow, not the cháng of length — and 長一長 is the casual doubling that makes an action sound small and offhand. Give it a bit of a stretch. It will not work.
Good Great Sage — he worked the sign, spoke a spell, and cried, "Grow!"
好大聖, good Great Sage, is the storyteller's applause line, dropped in just before he does something worth watching. The performer is cueing the audience.
At once he grew to some zhàng in height.
A 丈 zhàng runs to about three and a quarter metres, so this is a monkey suddenly the height of a house.
The bottle clung tight against his body and grew right along with him.
緊靠著身 takes the light zhe — pressed against him and staying pressed. This is the sentence that turns the scene.
He shrank himself down small, and the bottle shrank down with him too.
瓶兒 keeps 兒 at full weight as ér. And the symmetry is complete: it matches him in both directions, which means size is not the answer in either.
This is a genuinely elegant piece of trap design. Wukong's single most reliable trick across the whole novel is changing size — he has escaped a hundred situations by becoming enormous or becoming a gnat — and the bottle simply matches him. It does not resist him. It agrees with him, in both directions, which is worse.
The chapter is quietly making an argument here about what kind of thing this bottle is. A container you can break by growing is a container. A container that grows with you is a relationship, and the only way out of it will turn out to be the one the chapter title has been advertising since the first line: not force, not size, but a hole.