一事奉勞 One Matter To Trouble You
行者作禮道：「我有一事奉勞。」問：「何事？」行者道：「保唐僧西天取經，路遭險難。至西牛賀洲，有座山喚小西天，小雷音寺有一妖魔。行者作礼道：「我有一事奉劳。」问：「何事？」行者道：「保唐僧西天取经，路遭险难。至西牛贺洲，有座山唤小西天，小雷音寺有一妖魔。
逐句解 Line by line
Pilgrim made his bow and said, "I have one matter with which to trouble you."
奉勞 is deferential — putting someone to trouble on your own account. 行 is xíng.
He asked, "What matter?"
Two characters of question inside their own quotation marks, with the attribution in front. A unit that both names its speaker and closes its speech stands on its own, however short it is.
Pilgrim said, "Escorting the Tang Monk to fetch scriptures in the Western Heaven, we have met with peril on the road.
難 is nàn here, a disaster that has happened — not nán, meaning difficult. 險難 names the thing that has befallen them. The quotation opens here and does not close for several passages.
Coming to Aparagodānīya, there is a mountain called Little Western Heaven, and in the Monastery of Little Thunderclap there is a fiend.
西牛賀洲 is Aparagodānīya, the western continent. 小西天 and 小雷音 are both shrunken versions of the pilgrims' real destination — Little Western Heaven, Little Thunderclap — and the counterfeiting those names perform is the whole trick of the episode.
Monkey's request is preceded by a bow and six characters of formula, then he is asked what he wants and starts an account that runs for the rest of the scene. The proportions are deliberate: the asking is brief, the accounting is long.
The place names do the exposition. Little Western Heaven and Little Thunderclap are not descriptions but forgeries — the pilgrims' true goal is the Great Thunderclap, which this chapter names in its very last line, and a fiend has built a scale model of it on their road. Naming it is enough to explain how Tripitaka was taken in.
Nothing in the account is new to anyone who has just read the previous chapter. Its job is not to inform us but to let us watch Monkey admit, aloud and to a god, the sequence of his own failures.