滿面生春 His Whole Face Bloomed
三藏道：「貧僧乃東土大唐駕下差往西天大雷音寺取經者。卻才路過仙宮，竭誠進拜。」道士聞言，滿面生春道：「老師乃忠誠大德之佛，小道不知，失於遠候，恕罪，恕罪。」三藏道：「贫僧乃东土大唐驾下差往西天大雷音寺取经者。却才路过仙宫，竭诚进拜。」道士闻言，满面生春道：「老师乃忠诚大德之佛，小道不知，失于远候，恕罪，恕罪。」
逐句解 Line by line
"This poor monk," said Tripitaka, "was sent by the Tang court of the Eastern Land to the Great Thunderclap Monastery in the West, to fetch the scriptures."
He gives the whole warrant, and 差 is chāi, dispatched on official business — the second of the chapter's three, all of them this reading. 大雷音寺, the Great Thunderclap Monastery, is the journey's destination, the Buddha's own house. Twenty-three characters, and every one of them is the answer the Daoist was fishing for.
"We were just passing your immortal palace and came in with all sincerity to pay our respects."
仙宮, immortal palace, is flattery for a Daoist house — he is returning the courtesy of 寶山 in the appropriate register. 竭誠 is to exhaust one's sincerity, wholeheartedly. He is telling the exact truth in the politest available words.
At these words the Daoist's whole face bloomed. "Venerable master, you are a Buddha of loyalty and great virtue! This humble Daoist did not know, and failed to come out and meet you at a distance. Forgive me, forgive me."
滿面生春 is the tell, and it is a beautiful piece of writing: spring breaking out all over a face. It reads as delight, and it is delight — just not the kind the Tang Monk hears. 失於遠候, failing to wait for a guest at a distance from the door, is the most elaborate apology in the etiquette. And 恕罪，恕罪 doubled is the fourth doubled utterance in this chapter.
One sentence and the trap closes. Tripitaka is asked where he is from and he tells the truth — the full official truth, with the dispatching authority, the destination and the purpose. It is the answer of a man who has never once considered that being who he is might be the danger.
Then 滿面生春, spring breaking out over a face. The narrator has given us the man's real feeling in four characters, in a phrase that sounds like pure warmth. He is happy because the answer was yes. Everything he says next — Buddha of loyalty and great virtue, forgive me, forgive me — is genuine pleasure expressed as flattery.
The bitter joke is the flattery itself. He calls his guest a 佛, a Buddha, and apologises for not having come further out to meet him. In a few moments he will call for the tea to be changed. Both statements are made in the same warm voice by a man who is finally enjoying himself.