開鎖的積年 An Old Hand At Locks
八戒笑道：「開鎖有何難哉？不用刀斧，教我那一位毛臉老爺，他是開鎖的積年。」行者真個近前，使個解鎖法，用手一抹，幾把鎖俱退落下。那小和尚俱跑到廚中，淨刷鍋灶，安排茶飯。八戒笑道：「开锁有何难哉？不用刀斧，教我那一位毛脸老爷，他是开锁的积年。」行者真个近前，使个解锁法，用手一抹，几把锁俱退落下。那小和尚俱跑到厨中，净刷锅灶，安排茶饭。
逐句解 Line by line
Eight Rules laughed. "What is difficult about opening a lock?
難 here is the nán of difficulty, against the nàn of calamity four segments back. 哉 is a classical exclamation and sits oddly in Eight Rules's mouth, which is part of the joke.
"No need of knife or axe. Let that hairy-faced Reverence of mine do it — he is an old hand at opening locks."
積年 is a man of long standing at something, and applied to opening locks it means a practised thief. Eight Rules is calling his senior a burglar in front of strangers, and he is not wrong: the skill was picked up in heaven.
Pilgrim did indeed step up, worked a lock-loosing spell, passed his hand across them once, and the locks all fell away.
真個 concedes the joke — he does it, and he does it by magic rather than with the knife. 退落下 keeps luò and not the colloquial là. One pass of the hand, and a chapter's worth of iron comes off.
The young monks all ran off to the kitchen, scoured the pots and the stove clean, and got the meal ready.
俱跑 is the small detail that makes the passage: children who have been chained to a pillar run. And the first thing they do with themselves is start cleaning. 淨刷 looks forward to the sweeping — the chapter's business is dirt coming off things.
The rescue the whole community has been waiting for takes one gesture and arrives as a joke. Eight Rules will not use the knife, recommends his brother on the grounds that he is an experienced lock-breaker, and Pilgrim opens every lock in the courtyard with a spell and a wave of the hand.
The joke has an edge on it. Pilgrim's lock-opening is a skill from his career as a thief in heaven, and Eight Rules names it as such in front of the men being freed. The novel lets the disreputable past be exactly the thing that is useful here, and does not moralise about it.
What the children do with their freedom is the quietest thing in the chapter. They run to the kitchen and scrub it. The pots have presumably been standing as long as the censer in the hall has held cold ash.