大方廣佛華嚴經隨疏演義鈔 27.9

27.9

疏「天為圓穹」者，外典說天或謂有形，故云天形穹隆其形如𨫼，故天圓地方。若《莊子》云「天者自然也」，則無形質。

Regarding the commentary's: “The heavens are a round dome”: non-Buddhist texts state that heaven is perhaps regarded as having form; thus they say that the shape of heaven is domed and vaulted, its shape like an overturned pot, hence “heaven is round and earth is square.” If according to Zhuangzi, who says “heaven is natural spontaneity,” then it has no shape or substance.