首楞嚴義疏注經 8.354

8.354

隨順造惡，故受苦報。惡業不同受報亦別，故云自招。眾同分中有元地者，眾名不一，同是一義，眾有相似，同立分名，造業同者共中共變。《俱舍論》說「有差別同分、無差別同分。」同業共感眾多苦具同受此苦，名無差別同分。若隨輕重受報不同，名差別同分。今云元地，即差別也。

Following along in creating evil leads to undergoing bitter retribution. Evil karmas differ, so the retributions received are also distinct; hence it says 'brings this upon oneself'. As for 'within their common generic category there is an original ground': 'many' refers to diverse kinds, 'common' indicates a single principle; among the many there is similarity, so the name 'common category' is established, meaning those who create identical karma collectively transform within what is shared. The Abhidharmakośabhāṣya states: 'There are differentiated common categories and undifferentiated common categories.' Karma shared in common bringing about multiple instruments of suffering to undergo this pain together is named the undifferentiated common category. If one receives different retributions according to light and heavy degrees, it is called the differentiated common category. The present term 'original ground' refers to these differentiations.