俱舍論疏 12.40

12.40

論「於十八後至名第二十劫」，第四明後一劫唯增。此後一劫雖同十八，增至八萬，以增遲故，同前上下。

On the Śāstra's text, "After the eighteenth... it is named the twentieth kalpa": This is the fourth, explaining that the final one kalpa only increases. Although this final one kalpa is like the eighteen in increasing up to eighty thousand [years], because the increase is gradual, it is like the decreases and increases before.