俱舍論頌疏論本 23.72

23.72

斷次三向二者，第二向也。謂於凡位斷第六品或七、八品，名斷次三，謂前五品，次三品故。此有三人，此斷次三人至見道中名第二向，趣一來果故。

Regarding 'having abandoned the next three, one enters upon the second': this is the second enterer. That is to say, having abandoned the sixth category, or the seventh and eighth categories, in the stage of an ordinary person, this is called 'abandoning the next three', referring to the next three categories following the previous five categories. There are three such persons. When these persons who have abandoned the next three reach the path of seeing, they are called enterers upon the second [fruit], because they tend toward the fruit of once-returner.