俱舍論記 28.173

28.173

「一切唯一至未離下怖故」者，釋捨。一切近分唯一捨受相應。此近分定，起時艱辛作功用轉故、未離下染情懷怖故，非喜、樂相應。

Regarding 'All are associated solely with one ... because of fear of the lower not yet abandoned': this explains equanimity. All threshold states are associated solely with the feeling of equanimity. These threshold concentrations, when arising, operate with arduous effort, and because the mind harbors fear of the lower defilements not yet abandoned, they are not associated with joy or pleasure.