不好留此 No Reason To Detain Us Here
手下人請老爺客房安歇，三藏便走。行者恨道：「這廝憊懶，怎麼不讓老孫在正廳？」三藏道：「他這裡不服我大唐管屬，又不與我國相連，況不時又有上司過客來往，所以不好留此相待。」行者道：「這等說，我偏要他相待。」手下人请老爷客房安歇，三藏便走。行者恨道：「这厮惫懒，怎么不让老孙在正厅？」三藏道：「他这里不服我大唐管属，又不与我国相连，况不时又有上司过客来往，所以不好留此相待。」行者道：「这等说，我偏要他相待。」
逐句解 Line by line
Their underlings invited His Reverence to take his rest in the guest room, and Tripitaka went.
便走 — he simply goes, without a word. The narrator gives him no reaction to the room at all, which is what makes his disciple's reaction land.
Pilgrim said resentfully, "What slovenly wretches these are! Why will they not give old Sun the main hall?"
憊懶 is abuse for the shiftless and the insolent. 恨 here is not hatred but a grudging, resentful way of speaking.
Tripitaka said, "This place is not under the government of our Great Tang, nor does it share a border with our country; and besides, superiors and travellers pass through here at all hours. That is why it will not do to keep us here and entertain us."
好 is the ordinary hǎo in 不好留此 — it will not do — and not the hào that made verbs of the idlers in the street.
Pilgrim said, "Say what you like — I shall have them entertain us all the same."
偏 is the same contrary word he used below the city wall, doing the same work: not 'I want' but 'I shall, precisely because you say otherwise'.
Tripitaka's explanation is entirely reasonable and entirely beside the point. He answers a complaint about dignity with an account of jurisdiction, protocol and passing traffic, as though Pilgrim had asked why rather than objected that.
Pilgrim's reply refuses the reasoning without disputing it. 這等說 grants that the argument has been made; 我偏要 declares that it changes nothing.
The threat is idle in itself — nobody much cares which room they sleep in — but it sets the disposition the rest of the chapter runs on. Pilgrim has decided this kingdom is going to pay him proper attention, and he will find a way to make it.