俱舍論疏 1.263

1.263

論「若爾何緣生依二處」，難也。眼等三根既三義同，故雖二同界，何緣生依二處？自下半頌，第四明三根生二處所以。

Regarding the commentary statement "If so, for what reason are they born relying on two bases?": this is an objection. Since the three faculties such as the eye are identical in three respects and thus, though two, are the same dhātu, for what reason are they born relying on two bases? The half-stanza from here down fourthly clarifies the reason why the three faculties are born in two bases.