囑咐沙僧 Parting Words to Sha Monk
大聖跳起來，把身一抖，收上毫毛，卻又吩咐沙僧道：「賢弟，你是個好人，卻只要留心防著八戒詀言詀語，途中更要仔細。倘一時有妖精拿住師父，你就說老孫是他大徒弟，西方毛怪聞我的手段，不敢傷我師父。」唐僧道：「我是個好和尚，不題你這歹人的名字，你回去罷。」大圣跳起来，把身一抖，收上毫毛，却又吩咐沙僧道：「贤弟，你是个好人，却只要留心防着八戒詀言詀语，途中更要仔细。倘一时有妖精拿住师父，你就说老孙是他大徒弟，西方毛怪闻我的手段，不敢伤我师父。」唐僧道：「我是个好和尚，不题你这歹人的名字，你回去罢。」
逐句解 Line by line
The Great Sage sprang up, gave his body a shake, gathered back the hairs, and then charged Sha Monk: "Worthy brother, you are a good man — only take care to guard against Eight Rules' slanderous, nagging tongue, and be doubly careful along the way.
He shakes the doubles back into his skin, and then, before going, gives Sha Monk a briefing. 詀言詀語 — 詀 (zhān) is a rare character for insinuating, muttering talk — names precisely the thing that has just destroyed him, and he names it to the one member of the party who has kept his mouth shut all day. Watch him. Be careful on the road. (著 is zhe; 中 is zhōng; 仔 is zǐ, as in the master's 仔細仔細 at the top of the chapter.)
"Should a fiend ever seize the master, just tell them old Sun is his senior disciple: the vermin-monsters of the West, hearing of my powers, won't dare harm our master."
And then he leaves them the only thing he has left to give: his name. Tell them whose disciple he is, and the local monsters will not dare touch him. 毛怪, hairy fiends, is a faintly contemptuous word for the general run of demons. He is handing over his reputation as a piece of protective equipment, to a party that has just discharged him in writing.
The Tang Monk said, "I am a good monk — I'll not so much as speak the name of a wicked man like you. Off with you."
And it is refused. He will not so much as say the name. This is the fourth time in the chapter that the elder has told Wukong to go, and the third in these exact words. There is nothing left to take away from him now except the going itself.
Wukong's parting charge to Sha Monk crystallises the chapter's moral. Both his instructions are acts of care for the party that has expelled him: guard against Bajie's muttering, the slander that engineered his downfall, and — should a demon ever take the master — invoke his name, because the western fiends are afraid of him. He leaves behind a warning and a shield, thinking of nothing but Tripitaka's safety as he is driven off.
The advice about the name is quietly prophetic and quietly generous. Wukong knows his reputation alone can protect the master, and he offers it freely, asking nothing, guarding a man who has just sworn never to see him again. It is loyalty in its purest form, given with no hope of gratitude or return.
The elder's response is the last and coldest of his repudiations. He will not even mention Wukong's name — refusing the very protection he is being offered, rejecting his disciple so completely that he will not speak of him at all. The rupture is total. Wukong has given everything and the master has refused everything, and only the departure itself is left.