This is a quotation from Bhavartha-dipika, Sridhara Svami's commentary on Srimad-Bhagavatam (10.1.1). In the Tenth Canto of Srimad-Bhagavatam there is a description of the asraya-tattva, Sri Krsna. There are two tattvas-asraya-tattva and asrita-tattva. Asraya-tattva is the objective, and asrita-tattva is the subjective. Since the lotus feet of Lord Sri Krsna are the shelter of all devotees, Sri Krsna is called param dhama. In Bhagavad-gita it is stated: param brahma param dhama pavitram paramam bhavan. Everything is resting under the lotus feet of Krsna. In Srimad-Bhagavatam (10.14.58) it is stated:

Under the lotus feet of Sri Krsna, the entire mahat-tattva is existing. Since everything is under Sri Krsna's protection, Sri Krsna is called asraya-tattva. Everything else is called asrita-tattva. The material creation is also called asrita-tattva. Liberation from material bondage and the attainment of the spiritual platform are also asrita-tattva. Krsna is the only asraya-tattva. In the beginning of the creation there are Maha-Visnu, Garbhodakasayi Visnu and Ksirodakasayi Visnu. They are also asraya-tattva. Krsna is the cause of all causes (sarva-karana-karanam). To understand Krsna perfectly, one has to make an analytical study of asraya-tattva and asrita-tattva.