俱舍論疏 29.30

29.30

論「諸惑斷已至之所蔽伏」，釋惑。此能令已斷更遠。言「治四障」者，據令更遠說。

The Śāstra states: "After the various defilements have been severed... up to: being obscured and suppressed by them." This explains defilements. These can make what is already severed even further removed. The phrase "counteracting the four obstacles" is spoken in terms of making them further removed.