上黿之背 Onto the Turtle's Back
老黿卻才負近岸邊，將身一縱，爬上河崖。眾人近前觀看，有四丈圍圓的一個大白蓋。行者道：「師父，我們上他身，渡過去也。」三藏道：「徒弟呀，那層冰厚凍，尚且邅迍，況此黿背，恐不穩便。」老黿道：「師父放心。我比那層冰厚凍，穩得緊哩，但歪一歪，不成功果。」行者道：「師父啊，凡諸眾生，會說人話，決不打誑語。」教：「兄弟們，快牽馬來。」老鼋却才负近岸边，将身一纵，爬上河崖。众人近前观看，有四丈围圆的一个大白盖。行者道：「师父，我们上他身，渡过去也。」三藏道：「徒弟呀，那层冰厚冻，尚且邅迍，况此鼋背，恐不稳便。」老鼋道：「师父放心。我比那层冰厚冻，稳得紧哩，但歪一歪，不成功果。」行者道：「师父啊，凡诸众生，会说人话，决不打诳语。」教：「兄弟们，快牵马来。」
逐句解 Line by line
The old turtle then bore himself close to the bank, gave a heave of his body, and clambered up onto the river-cliff.
老黿 keeps 黿 as yuán; 將身一縱 takes 將 as jiāng. He hauls himself up onto the bank, which is chiefly so that the villagers can measure him.
The people came near to look, and saw a great white shell four zhàng round in circumference.
觀看 takes 觀 as guān and 看 as kàn. 四丈 stays in Chinese measure as four zhàng — around forty feet round, which makes this the largest living thing in the chapter by a wide margin. 圍圓, in circumference.
Pilgrim said: "Master, we will get up on his body and cross over."
上他身, to get up on his body. Wukong proposes the turtle as a ferry, and his master's fear supplies the rest of the scene.
Tripitaka said: "Disciple, even that thick ice of the frozen layer was hard going and slippery; how much less safe will this turtle's back be?"
三藏 keeps 藏 as zàng; 那層冰 points, nà; 黿背 takes 黿 as yuán and 背 as the noun bèi. 邅迍 (zhān zhūn) is a pair of syllables for stumbling and heavy going. He is remembering the ice of chapter 48, and remembering it accurately.
The old turtle said: "Set your mind at rest, master.
老黿 keeps 黿 as yuán. The turtle answers the fear head-on and on its own terms, which nobody else in the scene thinks to do.
I am far steadier than that thick ice of the frozen layer. If I so much as tilt a hair's breadth, I do not accomplish the fruit of merit."
那層冰 points, nà; 穩得緊 keeps 得 as dé; 哩 is the spoken tag, li. 功果 is the fruit of merit — the payoff of centuries of practice. He is staking his entire cultivation on not tipping, which is a considerable bond to post.
Pilgrim said: "Master, among all living creatures, one that can speak human speech will surely not tell a lie."
決不打誑語: 誑 is kuáng, to deceive, and 打誑語 is to tell a lie. Here is the principle stated plainly — human speech is a guarantee of good faith — offered to calm his master. In the passage just before, faced with the same creature, Wukong did not think it sufficient for a moment.
He gave the order: "Brothers, be quick and lead the horse over."
教 jiào, "ordered." The passage ends with the party moving to mount, and the crossing about to begin.
This is a study in the difference between two river crossings. In chapter 48 the pilgrims crossed on ice, and the ice betrayed them — it broke, and the demon took the master down. Tripitaka remembers it exactly, and his fear of the turtle's back is the fear of being let down by a surface a second time: 那層冰厚凍，尚且邅迍, even that thick ice was treacherous going. The turtle answers on the fear's own terms — I am steadier than the ice was — and stakes his accumulated merit on it. The contrast is deliberate. The dead ice failed them; the living creature will not.
Wukong's reassurance carries an irony the chapter has been setting up with some care. He tells his master that a creature able to speak human words 決不打誑語, will surely not lie, and offers this as sufficient grounds for climbing onto forty feet of river turtle. Yet in the passage immediately before, faced with the same animal, he did not find it sufficient at all: he made it swear an oath to Heaven on pain of dissolving into blood.
The novel does not point at the inconsistency. It simply lets Wukong be the suspicious interrogator when his own safety is in question and the trusting reassurer when his master needs calming, which is true to him from one end of the book to the other.