俱舍論頌疏論本 29.15

29.15

二二一一定者，謂二二定，一一定也，上二謂初二解脫，下二謂初二靜慮，以初二解脫依初二靜慮起，名二二定也。一一定者，一謂第三解脫，此一解脫唯依第四禪起，名一一定也。以第四禪離八災患，心澄淨故，有淨解脫。

"[Occurring in] two, two, and one, one concentration": this means two in two concentrations, and one in one concentration. The upper "two" refers to the first two liberations; the lower "two" refers to the first two dhyānas. Because the first two liberations arise relying on the first two dhyānas, they are called "two in two concentrations." "One in one concentration": "one" refers to the third liberation; this single liberation arises relying solely on the fourth dhyāna, hence it is called "one in one concentration." Because the fourth dhyāna is free from the eight afflictions and the mind is clear and pure, the pure liberation exists there.