金剛經纂要刊定記 4.115

4.115

為求下。指疑起處也。此從不住相布施中來，為聞前不住三世空有等相方名真施，遂疑云：「凡所行施蓋為求佛，既有所求云何無住？」

Regarding "for the sake of seeking, etc.": this points to the origin of the doubt. This arises from giving without abiding in marks: having heard earlier that not abiding in the marks of the three times, emptiness, existence, and so on is alone called true giving, one subsequently doubted: 'All practice of giving is done to seek Buddhahood; since there is something sought, how can there be non-abiding?'