成唯識論演祕 5.89

5.89

答：前之二定當動勇故，悅根方樂，故舉言之。第三安靜不唯對根，方稱為樂，故不言也，理實悅根逾於前矣。

Answer: Because the previous two absorptions involve agitation and boldness, it is only upon gratifying the faculties that it is pleasure, and therefore it is mentioned. In the third [dhyāna], it is tranquil and calm; it is not called pleasure only in relation to the faculties, so it is not mentioned; in principle, its gratification of the faculties actually surpasses the previous ones.