俱舍論疏 1.264

1.264

「論曰至身不端嚴」，釋中有二：一有部釋、二論主破。此文初也。為令身端嚴故，所以生二；身舌生二即不端嚴，如串子并，及如蛇兩舌故。廣如《婆沙》。若眼、耳、鼻唯有一者，即身不端嚴，故各生二。

Regarding the commentary statement from "The text says" up to "the body would not be well-proportioned": in the explanation there are two parts: first, the Vaibhāṣika explanation; second, the author's refutation. This is the first part of the text. In order to make the body well-proportioned, they are born as two; if the body and tongue were born as two, it would not be well-proportioned, like joined twins or a snake's bifurcated tongue, as detailed in the Vibhāṣā. If the eye, ear, and nose were only single, the body would not be well-proportioned, so each is born as two.