洞門開了 The Cave Door Opens
行者上前叫：「牛大哥，開門，開門。」呀的一聲，洞門開了，裡邊走出一個毛兒女，手中提著花籃，肩上擔著鋤子。真個是一身藍縷無妝飾，滿面精神有道心。行者上前叫：「牛大哥，开门，开门。」呀的一声，洞门开了，里边走出一个毛儿女，手中提着花篮，肩上担着锄子。真个是一身蓝缕无妆饰，满面精神有道心。
逐句解 Line by line
Pilgrim went up and called, 'Brother Bull! Open the door, open the door!'
牛大哥, "Elder Brother Bull." Pilgrim announces himself by claiming an old sworn brotherhood with the Bull Demon King, and does it before the door is even open. It is a calculated opening, and it is about to be answered by a servant.
With a creak the cave door opened, and out came a hairy girl, a flower basket in her hand and a hoe over her shoulder.
呀 is the sound-word yā, a door creaking, not the weightless ya that closes a sentence. In 毛兒女 the 兒 is the curled-back ending; she is called plain 毛女 a few lines later. Both 著 mark actions in progress, zhe, and 擔 is dān, to carry on a shoulder pole.
She was indeed all in rags and without an ornament on her, yet her whole face was alive with the mind of the Way.
真個是 announces a balanced couplet, but 維基文庫 does not set it as indented verse, so it stays in the prose and the passage keeps three chips. The source's layout decides this, not the phrase. 藍縷 is ragged; 道心 is the mind set on the Way.
Pilgrim's opening move is a gamble, and he makes it before anybody can even see him. 牛大哥 — Elder Brother Bull — claims the sworn brotherhood he formed with the Bull Demon King five hundred years ago, and he shouts it at a closed door. He is establishing a relationship in advance of any conversation, which is the opposite of what the woodcutter told him to do.
What answers is not the Bull Demon King. A door creaks, and out comes a hairy girl with a flower basket and a hoe — a servant, dressed in rags, who has been gardening. The deflation is deliberate and it is also information: the household runs to one attendant doing manual work, and the husband whose name Pilgrim has just invoked is evidently not at home.
The couplet describing her is the chapter's clearest case of a poem that is not set as one. 真個是 introduces a perfectly balanced pair of lines — all in rags and without an ornament, yet her whole face alive with the mind of the Way — but the source does not indent it, so it stays in the prose. The novel is telling us she is more than a maidservant while keeping her, on the page, part of the scenery.