大方廣佛華嚴經隨疏演義鈔 61.40

61.40

疏「初禪離欲大障」者，約障大小解，離欲大障，初名離生。二無大障，二不名離。

Regarding the commentary's "The first dhyāna is separated from the great obstacle of desire": explaining in terms of the size of obstacles, being separated from the great obstacle of desire, the first is called 'born of separation'. The second lacks a great obstacle, so the second is not called 'separation'.