俱舍論記 17.98

17.98

「不言人壽至令不久住」者，答。不言人壽即是殺生不善業果，但言由殺，人壽量短。殺業與命作障礙因，令不久住。

"It is not said that human lifespan... causes it not to abide long" is the answer. It is not said that the human lifespan itself is the fruit of the unwholesome karma of taking life; it only says that due to taking life, the measure of human life is short. The karma of killing serves as an obstructive cause to life, causing it not to abide long.