His teacher was Xuedou Zhijian[1] (雪竇智鑑, 1105–1192), who was the sixteenth-generation dharma descendant of Huineng.
According to Keizan, when Ruijing became a leader, he didn't put himself above the other monks. He wore the black surplice and robe of a monk. He was given a purple vestment of honor by the emperor of China, but he declined it. Even after reaching enlightenment, he was willing to clean the bathroom.[3]
He is traditionally the originator of the terms shikantaza[4] and shinjin-datsuraku ("casting off of body and mind").