大方廣佛華嚴經隨疏演義鈔 33.65

33.65

疏「如鳥在殼」者，殼為鳥卵，為母所附者。言「含聲未吐」者，庾信云：「團團竹上禽，白玉裏黃金，裏有思晨鳥，含聲未吐音。」借其言用。

Regarding the commentary's "Like a bird in an eggshell": the shell is the bird's egg, incubated by the mother. Regarding "containing its voice and not yet uttering it": Yu Xin said, / "A plump bird on the bamboo, / gold inside white jade; / within it is a bird contemplating the dawn, / containing its voice and not yet uttering a sound." / It borrows his words for use.