俱舍論疏 24.112

24.112

論「空處四十至二十四」，明無色漸減。空處無二法智，及除四滅、四道，總十諦，一一有四，故除四十。識處減八，謂滅、道各四，故三十二。無所有處又更除八，故二十四也。

The Śāstra says: "In the sphere of infinite space there are forty […] twenty-four." This explains the gradual decrease in the formless realm. The sphere of infinite space lacks the two dharma knowledges, and excludes four cessations and four paths, making ten truths in total, each having four [aspects]; hence forty are eliminated. The sphere of infinite consciousness is reduced by eight, namely four each of cessation and path, thus having thirty-two. The sphere of nothingness further eliminates eight, thus having twenty-four.