瑜伽論記 17.436

17.436

次釋其名。靜心思慮，故名靜慮，支是分義，相隨順義，亦是因義，名靜慮支。薩婆多說：定是靜慮支，餘是靜慮支攝非靜慮。如實義者如四支軍，各對治故，捨念正智三依於定位，因能除障名內等淨，淨諸障故，餘名可解。

Next is the explanation of its name. Quieting the mind and thinking/deliberating, it is therefore called "calm reflection" (dhyāna). A "limb" (aṅga) has the meaning of a component, the meaning of being compliant/conducive, and also the meaning of a cause; hence they are called "dhyāna limbs". The Sarvāstivāda says: Concentration is a dhyāna limb, and the rest are included within the dhyāna limbs but are not themselves dhyāna. As for the real meaning: like a four-division army, they serve as specific antidotes respectively. Equanimity, mindfulness, and correct knowledge, these three depend upon the state of concentration; because they can eliminate obstacles, they are called "inner equal purification", for they purify all obstacles. The remaining names can be understood.