三分人相 He Still Looked Part Human
今夜做的甚麼惡夢，遇著這夥惡人？為先的那和尚醜便醜，還有三分人相；今夜做的甚么恶梦，遇着这伙恶人？为先的那和尚丑便丑，还有三分人相；
逐句解 Line by line
"What sort of evil dream did I have last night, to run into a gang of monsters like this?
遇著 has 著 as zháo, the band of contact achieved — running into something, meeting it — which is the fourth appearance of this character in the chapter and its third distinct reading. 惡夢 and 惡人 put the same character twice in one sentence, once for the dream and once for the men in it.
The monk who came first was ugly, but he still had three parts of a human look about him;
為先的 is the one that came first, with 為 as wéi, the copula. 三分人相 is the phrase to keep: three parts out of ten of a human appearance, which is measurement rather than insult and all the funnier for it. 相 is xiàng, outward appearance, not the xiāng of mutual.
The old man's first thought is that he is dreaming, which is the only reasonable explanation available to him and happens to be wrong. He has been awake all day and the day has simply been like this.
Then he starts grading. The first monk was ugly but retained three parts in ten of a human look — a fraction, offered seriously, as though there were a scale. It is the funniest line in the chapter so far and the old man does not know he has made a joke.