大方廣佛華嚴經疏 19.48

19.48

二徵釋所由中，初徵意云：何以發心即得果法？釋云：以是發心為因，決定當得佛故。望圓極之果，故定當成。約見性成智身，上品云即得故。晉經、梵本此中皆云即是佛故者，當此義也。

In the second, questioning and explaining the cause, the first question's intent is: Why does generating the mind immediately attain the fruit dharmas? The explanation says: Because, taking this generation of the mind as the cause, one will definitely attain Buddhahood. With respect to the consummate, ultimate fruit, it will definitely be accomplished. In terms of seeing the nature to accomplish the wisdom-body, the previous chapter says it is immediately attained. The Jin translation and the Sanskrit texts both state here that "one is immediately a Buddha", which corresponds to this meaning.