大般涅槃經義記 4.145

4.145

自下第三辨明闡提不畏所以，并教菩薩對治捨離。先舉偈文，「作惡不即受，如乳即成酪」辨明闡提不畏所以。乳得醪煖，交變成酪；作惡不爾，現在造作，未來方受，不能即時交受苦果，如乳成酪。「猶灰覆火，愚者輕蹈」正明無畏。現報如灰，當苦如火，現報隔障說之為覆，愚人輕欺，造惡臨逼，名之為蹈。

From here on, the third [part] explains the reason why the icchantika has no fear, and teaches the bodhisattva to counteract and abandon it. First, it cites the text of the verse: "Committing evil and not immediately receiving it, like milk immediately turning into curds" explains the reason why the icchantika has no fear. When milk receives starter and warmth, it transforms into curds; committing evil is not like this: it is created in the present and only received in the future; one cannot immediately receive the painful fruit on the spot, as milk turns into curds. "Like ash covering fire, the fool treads lightly on it" directly explains lack of fear. The present retribution is like ash; future suffering is like fire. The obstruction of present retribution is described as "covering"; the fool treats it lightly, and creating evil approaches peril, which is called "treading."