俱舍論記 8.124

8.124

「鬼趣唯通至雖盡而無飽」者，釋第六句。鬼化生可知，胎生難知，故引頌證。卵、濕生類性多愚癡。鬼多黠慧，故非卵、濕。

Regarding "The ghost destiny admits only of [...] although exhausted, there is no satisfaction": this explains the sixth line. Apparitional birth among ghosts can be understood; womb-birth is difficult to know, hence the verse is cited as proof. The classes of egg-born and moisture-born beings are mostly foolish by nature. Ghosts are mostly sharp-witted and intelligent; therefore, they are not egg-born or moisture-born.