虔心求授 They Bow and Beg to Learn
那王子聽言，個個頂禮不盡。三個向前重重拜禮，虔心求授。行者道：「你三人不知學那般武藝？」那王子听言，个个顶礼不尽。三个向前重重拜礼，虔心求授。行者道：「你三人不知学那般武艺？」
逐句解 Line by line
The princes heard him out, and every one of them bowed without ceasing.
頂禮 is the deepest reverence there is, the one that puts the crown of the head at another's feet, and 不盡 means they could not finish doing it. The doubled 個個, one and one, counts them one by one.
The three came forward and bowed again and again with all reverence, begging with sincere hearts to be taught.
重重 is read chóng chóng here, over and over — not the zhòng that means heavy, which the same character carries at seven of its nine appearances in this chapter. 虔心, a reverent heart, is the phrase their father used when he first made the request, and the sons repeat it.
Pilgrim said, "Which of the arts do you three not know, and would learn?"
那 is nǎ here, which — the question word, not the pointing one. It is the first thing Pilgrim has asked the boys rather than told them, and the answer they give is the sentence that assigns each of them to a master.
The performance is over and the transaction begins. Pilgrim asks what they want to learn, which is the first question he has put to them.
It is also the moment he stops showing off. Twelve couplets about his own weapon, and then a plain enquiry about what these three actually need.