家常相待 Entertained as of the House
只見一僮又請進早齋。到廳上吃畢。敘不多時，又午齋相繼而進。三藏見品物豐盛，再四不安道：「既蒙見留，只可以家常相待。」陳老道：「老爺，感蒙替祭救命之恩，雖逐日設筵奉款，也難酬難謝。」只见一僮又请进早斋。到厅上吃毕。叙不多时，又午斋相继而进。三藏见品物丰盛，再四不安道：「既蒙见留，只可以家常相待。」陈老道：「老爷，感蒙替祭救命之恩，虽逐日设筵奉款，也难酬难谢。」
逐句解 Line by line
Then a boy came to invite them in to the early meal.
早齋 is the morning meal of a religious house. The Chens are keeping monastic hours for their guests.
They went to the hall and finished it.
Four characters of narrative dispatch. The novel is marking time on purpose.
They had not talked long before the midday meal followed on after it.
相繼: 相 is xiāng, one thing following another — not xiàng, "appearance."
Tripitaka, seeing the dishes so lavish, was uneasy over and over, and said: 「Since you are good enough to keep us, plain household fare would serve.」
家常相待: 相 is xiāng again, standing in front of the verb — to treat a man as one of the household. 再四, over and over.
Old Chen said: 「Your reverence, for the kindness of standing in our stead at the sacrifice and saving those two lives, though we set out a banquet every day of our lives we could never repay nor thank you enough.」
難酬難謝: 難 is nán, "hard to," twice. 替祭 is to sacrifice in another's place, and it is the phrase that names exactly what Wukong and Eight Rules did on that altar.
A short interval of meals, doing structural work. The days are passing, the river is freezing, the pilgrims are being fed. Old Chen's phrase for what he owes them — 替祭救命之恩, the kindness of sacrificing in our stead and saving lives — sets down the whole moral account of the Chen Village episode in six characters, and it is why the household will not let them leave quietly.
Tripitaka's discomfort at the lavishness is in character and, in the circumstances, faintly ironic. He asks to be treated 家常, as one of the household, while growing more frantic by the day to be gone from it.