Which Bhakti saint preached the concept of Vishishtadvaita?

Ramanuja, the main proponent of Vishishtadvaita philosophy contends that the Prasthanatrayi ("The three courses"), namely the Upanishads, the Bhagavad Gita, and the Brahma Sutras are to be interpreted in a way that shows this unity in diversity, for any other way would violate their consistency. Vedanta Desika defines Vishishtadvaita using the statement, Asesha Chit-Achit Prakaaram Brahmaikameva Tatvam : Brahman, as qualified by the sentient and insentient modes (or attributes), is the only reality.