俱舍論頌疏論本 7.44

7.44

無覆從三生者，謂色界無覆無記從三心生，謂自界三，餘無生理。

"Unimpeded arises from three": this means that the unimpeded neutral of the form realm arises from three minds, namely, the three of its own realm; there is no principle [by which it arises] from the rest.