When master and disciples had journeyed a good while, once more a mountain rose to bar the road.

行罷 (xíng bà) "having walked," with 罷 marking completion. A fresh mountain means a fresh adventure — the novel's basic episodic rhythm.

From his saddle Tripitaka called out: “Disciples! Look how craggy and towering the mountain stands there. We must be careful and on our guard — I fear some demon-obstacle may again beset us.”

崔巍 (cuī wēi) "lofty and steep"; 隄防 = 堤防, "to guard against." 魔障 (mó zhàng) is a Buddhist term — the demonic obstructions that block the road to enlightenment; here the literal monster and the spiritual hindrance are one and the same. 仔 is read zǐ (仔細); both 那 are the demonstrative nà.

The Pilgrim said: “Master, don't let your thoughts run wild. Only steady your nature and keep your spirit whole, and of themselves there will be no troubles.”

定性存神 (dìng xìng cún shén) "to fix the nature and preserve the spirit" — inner-alchemical language for mental composure. Sun Wukong, the 心猿 ("mind-monkey"), here counsels exactly the disciplined calm the whole chapter is about.

Tripitaka said: “Disciple, why is the Western Heaven so hard to reach?”

難行 (nán xíng) "hard to travel." Tripitaka's recurring impatience over the distance sets up the comic exchange that follows.

“As I recall, since we left the city of Chang'an, spring has ended and summer come, autumn faded and winter arrived, four or five years running — and still we cannot get there?”

長安 (Cháng'ān), the Tang capital (modern Xi'an), read with 長 as cháng. The seasonal catalogue conveys the passage of years. Note the one graph 得 read two ways in a single sentence: 記得 (jìde, "remember") and 得到 (dédào, "reach").

Hearing this, the Pilgrim laughed aloud: “Early days, early days — we haven't even stepped out the front gate yet.”

A comic hyperbole that runs through the whole passage: the road is so vast that all their years of travel have not brought them past the ‘front door.’ 還 is read hái ("still, yet").

Eight Rules said: “Brother, don't tell tall tales.”

扯謊 (chě huǎng) "to tell lies." Zhu Bajie, ever literal-minded, takes the metaphor for a boast.

“What house in the world has a gate that big?”

Bajie's objection is entirely practical: no real dwelling could have so vast a gate. The joke depends on his mistaking a figure of speech for a claim about architecture.

The Pilgrim said: “Little brother, we're still just wandering about in the main hall.”

堂屋 (táng wū) the central hall of a house. The Pilgrim doubles down on the conceit: not the gate — they have not even crossed the front room.

Sha the Monk laughed: “Elder brother, spare us the big talk meant to frighten us.”

Sha Monk plays the sensible foil, pretending to take the boast as an attempt to overawe them.

“Wherever would there be a main hall so vast — and nowhere could you buy a ridge-beam so huge!”

那裡 here is rhetorical — ‘wherever would there be…’ — and so 那 is read nǎ, not the demonstrative nà. 過梁 (guò liáng) the main crossbeam of a roof.

The Pilgrim said: “Brothers, the way old Sun sees it — take the blue sky for roof-tiles, sun and moon for window-lattices, the four mountains and five peaks for beams and pillars, and Heaven and Earth are like one open hall.”

A cosmic comic conceit: the universe itself is the ‘great house’ they are crossing. 四山五岳 evokes the sacred marchmount-peaks (五岳). Both instances of 為 mean "to serve as, take as," read wéi. 窗櫺 (chuāng líng) window-lattice.

Hearing this, Eight Rules said: “Enough, enough — let's just count it as strolling about a while and go home.”

只當 (zhǐ dàng) "to treat it merely as," with 當 in its ‘reckon-as’ sense. The two 罷了 are exasperated ("enough!"); the final 罷 is the suggestive particle ba. Bajie's comic urge to give up recurs at every hardship.

The Pilgrim said: “No need for idle chatter — just keep following old Sun and walk on.”

跟著 (gēnzhe) "following," durative; 不必 (búbì) "no need," 不 in fourth-tone sandhi before 必.