俱舍論疏 2.25

2.25

「論曰至具足十八」，第二長行釋也。釋三界即為三段，此第一釋欲界繫也。繫謂繫屬，即被縛義。將辨法多少，先釋繫義。欲界繫法，被欲界貪等繫縛，名欲界繫。即鼻、舌、香、味四界全，餘十四界一分，是欲界繫。由此欲界具十八。

The commentary says: "The treatise says... fully possesses eighteen." This is the second [part], the prose explanation. The explanation of the three realms is divided into three sections; this is the first, explaining bondage to the desire realm. "Bound" (pratibaddha/saṃyukta) means tied to, namely the sense of being fettered. Prior to analyzing the number of phenomena, it first explains the meaning of "bound." Phenomena bound to the desire realm are fettered by desire-realm greed and so forth, and are therefore called bound to the desire realm. Namely, the four dhātus of nose, tongue, smell, and taste in their entirety, and a portion of the remaining fourteen dhātus, are bound to the desire realm. Because of this, the desire realm fully possesses eighteen.