安排個草鋪 A Straw Bed Behind The Guardian
那僧謝道：「既老師寬厚，請他到天王殿裡，就在天王爺爺身後，安排個草鋪，教他睡罷。」三藏道：「甚好，甚好。」那僧谢道：「既老师宽厚，请他到天王殿里，就在天王爷爷身后，安排个草铺，教他睡罢。」三藏道：「甚好，甚好。」
逐句解 Line by line
The monk thanked him and said, "Since the master is so generous, let her be taken to the Hall of the Heavenly Kings, and there behind His Lordship the Heavenly King let a straw pallet be arranged, and let her sleep there."
罷 is the unstressed ba here, the softener that turns an instruction into a suggestion — the opposite of the full verb bà two passages back. 鋪 is pù, a plank or straw bed. The 天王 are the four Heavenly Kings who guard the gate of every Chinese monastery, armoured giants with swords and serpents.
Tripitaka said, "Very good, very good."
甚 is shèn in both of these, the intensifier very — the same character that was the question word what in the previous passage.
The solution is a compromise everyone can live with: not in the monks' quarters, not turned out into the night, but on straw behind the biggest and most heavily armed statue in the building.
The placement is the novel's joke and the novel's warning at once. She is put under the protection of the guardian kings, and she is a fiend, so she is in fact being tucked in behind the very figures whose job is to keep her kind out. The Heavenly Kings will guard nothing tonight.
Tripitaka's reply is four characters of untroubled approval. He has solved a housekeeping problem and can now go to bed.