金剛經纂要刊定記 7.25

7.25

云何下。結成疑也。眾生用者。據佛壽量合滿百年，至八十便入涅槃，意留二十年福，與後代弟子受用。又於佛供養承事，能令眾生獲福無量，斯亦佛福眾生受用也。

From "How..." onward concludes by forming the doubt. "Sentient beings enjoy": Based on the Buddha's lifespan, it should have completed a full hundred years; when reaching eighty, he entered nirvāṇa, intending to leave twenty years of merit for later disciples to enjoy. Furthermore, making offerings and rendering service to the Buddha enables sentient beings to obtain immeasurable merit; this also means that sentient beings enjoy the Buddha's merit.