大乘百法明門論開宗義決 1.248

1.248

斷伏隨收故合為四者。即合想受不動二種。隨入擇滅及非擇滅。即唯有四故五蘊等說四無為。

Regarding "because severance and subduing are subsumed accordingly, they are combined into four": this means that the two—[cessation of] conception and feeling, and imperturbability—are combined, and subsumed under analytical cessation and non-analytical cessation; thus there are only four, and so the Pañcaskandhaka and other texts speak of four unconditioned dharmas.