俱舍論疏 28.6

28.6

「論曰至靜慮差別」，此述先說靜慮所以。諸功德多依此四，故先辨也。

"The Śāstra says: ... differences among dhyānas." This explains the reason for first discussing dhyāna. Many virtues rely mostly on these four; therefore they are distinguished first.