俱舍論記 8.109

8.109

「若爾何故至五蘊為體」者，難。經言於識有喜、染故，識住其中，識所乘御；又說識體為七識住，明知識體亦是所住。

Regarding "If so, why [...] having the five skandhas as their nature?": this is an objection. The sūtra says that because there are delight and passion toward consciousness, consciousness abides within it and is ridden by consciousness; furthermore, it speaks of the substance of consciousness as the seven stations of consciousness, which makes it clear that the substance of consciousness is also what is abided in.