守山大神 The Mountain-Guardian
那菩薩早已看見行者來到，即命守山大神去迎。那大神出林來，叫聲：「孫悟空，那裡去？」行者擡頭喝道：「你這個熊羆，悟空可是你叫的？當初不是老孫饒了你，你已是做了黑風山的屍鬼矣。今日跟了菩薩，受了善果，居此仙山，常聽法教，你叫不得我一聲『老爺』？」那黑熊真個得了正果，在菩薩處鎮守普陀，稱為大神，是也虧了行者。他只得陪笑道：「大聖，古人云：『君子不念舊惡。』只管題他怎的？菩薩著我來迎你哩。」這行者就端肅尊誠，與大神到了紫竹林裡，參拜菩薩。那菩萨早已看见行者来到，即命守山大神去迎。那大神出林来，叫声：「孙悟空，那里去？」行者抬头喝道：「你这个熊罴，悟空可是你叫的？当初不是老孙饶了你，你已是做了黑风山的尸鬼矣。今日跟了菩萨，受了善果，居此仙山，常听法教，你叫不得我一声『老爷』？」那黑熊真个得了正果，在菩萨处镇守普陀，称为大神，是也亏了行者。他只得陪笑道：「大圣，古人云：『君子不念旧恶。』只管题他怎的？菩萨着我来迎你哩。」这行者就端肃尊诚，与大神到了紫竹林里，参拜菩萨。
逐句解 Line by line
The Bodhisattva had already seen the pilgrim coming, and at once bade the Mountain-Guardian go to meet him.
守山大神, the Great Guardian of the Mountain, is Guanyin's doorkeeper on Potalaka -- and, as the next lines reveal, an old acquaintance of Wukong's in a very different capacity.
The Guardian came out of the grove and called, "Sun Wukong — where do you think you're going?"
那裡去, where do you think you're going, with 那 in its question reading nǎ. Being challenged at the gate by a defeated enemy is not something Wukong is going to let pass.
The pilgrim looked up and barked, "You bear-brute — is 'Wukong' a name for the likes of you to bandy?"
熊羆 is a bear, 羆 = pí, the brown kind -- a jab at the Guardian's origins. He is the Black Bear spirit, and Wukong is not about to be hailed by first name by somebody he once beat.
"Had old Monkey not spared you at the start, you'd be a corpse-ghost of Black Wind Mountain by now."
當初 is at the outset, 當 = dāng. 黑風山, Black Wind Mountain, recalls the episode in which Guanyin and Wukong together subdued the Black Bear spirit and set him to guard her mountain.
"And now, following the Bodhisattva, having gained a good reward, dwelling on this immortal mountain and hearing the Dharma daily — can't you even call me 'sir'?"
善果 is good fruit -- the favourable outcome of good karma, a reward earned rather than given. 叫不得 is cannot bring yourself to call, with 得, toneless de, asking whether the thing is even possible. Wukong stands on his seniority right up to the Bodhisattva's door.
The Black Bear had indeed attained the true fruit, guarding Potalaka in the Bodhisattva's service and styled a Great Guardian — and for that, in truth, he had the pilgrim to thank.
The narrator steps in with the point Wukong has missed. 得了正果 is attained the true fruit, 得 = dé; 稱為大神 is styled a Great Guardian, 為 = wéi, the copula. 虧了行者 is owing it to the pilgrim -- the Bear's blessed situation is the direct result of the defeat Wukong keeps throwing in his face.
He could only force a smile and say, "Great Sage, the ancients had it: 'The gentleman bears no grudge for old wrongs.'"
君子不念舊惡, the gentleman does not dwell on old wrongs, is from the 論語, and quoting Confucius at a monkey who is bullying you is a small masterpiece of tact. 只得 is could only, had no choice, 得 = dé; 子 in 君子 is the noun zǐ.
"Why keep bringing it up?"
只管 is to keep on, to persist in; 題 stands for 提, to bring up. Why keep raking it up -- the polite version of let it go.
"The Bodhisattva sent me to welcome you."
著我來迎 is dispatched me to come and greet you. 著 here is the verb to arrange or command, read zhuó -- the 廣韻 spells it 張略切, and the same literary reading lies behind the old edict formula 著即施行, let it be carried out forthwith. This is a different creature from the zhe that marks an action going on and from zháo that marks one landing, and different again from zhāo, which is kept for the board-game move (一著棋) and the clever stroke (高著兒). One character, four jobs.
At this the pilgrim composed himself into grave respect, and went with the Guardian into the purple bamboo grove to pay homage to the Bodhisattva.
端肅尊誠 is grave, respectful and sincere -- four characters that reverse Wukong's posture in a single beat. 紫竹林 is the purple bamboo grove, Guanyin's seat on Potalaka.
The turn into Guanyin's realm brings a small, satisfying grace-note: the Mountain-Guardian who challenges Wukong at the grove is the Black Bear spirit he and the Bodhisattva subdued some chapters back and posted to this very gate. Their exchange is prickly -- the Bear needling, Wukong lording his old victory and demanding to be called sir -- but the narrator's aside makes the deeper point. The Bear's present blessedness, his good karma and his station on Potalaka, is owed precisely to the defeat Wukong is throwing in his face. In this novel's accounting, losing is often how one gets somewhere.
The scene also shows Wukong's two faces inside a few lines. To the Bear he is all bluster and wounded seniority; the moment the Bodhisattva is named, he composes himself into grave respect and goes in to bow. The speed of the switch measures the one authority he genuinely reveres, and sets the register of humility in which he is about to make the plea the whole chapter has been building toward.