Ten years passed between the death of his teacher Zhantang Wenzhun in 1115 and the day another master accepted his awakening, and by his own account Dahui Zonggao spent them doubting: his own attainment, his teachers, and whether Chan was still alive in his time. He had trained in more than one line. As a young monk he studied Yunmen's sayings, served a Linji teacher, and in two years at Taiyang monastery mastered, as he later put it, the essentials of the Caodong house. In 1125, under Yuanwu Keqin, the Linji master who compiled the Blue Cliff Record, he broke through at the Tianning monastery in the capital, and he later said that if Yuanwu had approved him as easily as his earlier teachers had, he would not have believed there was a Chan school at all.
Doubt became his method. Take one word from an old story, the wu, "no", that Zhaozhou gave when a monk asked whether a dog has the Buddha-nature, and hold it day and night with all the doubt you have, until the doubt breaks. The practice is called kanhua, watching the phrase. Dahui meant it for people who could not leave the world. The scholar-officials who sought him out had offices, families and political enemies, and he urged them to practise for themselves rather than merely fund monasteries; the drama of the phrase, he judged, lay more within their reach than quiet sitting. From 1134 he attacked teachers who, as he saw it, told such men to quiet their minds into cold ash and dead wood, and he called their way the heretical Chan of silent illumination. Morten Schlütter, a historian of Song Chan, has argued that his target was the Caodong line revived in the early twelfth century; whether he meant Hongzhi Zhengjue, its most famous abbot, is disputed. The two men were colleagues, and Hongzhi never answered him.
In 1137 he became abbot of the Nengren monastery on Mount Jing, near Hangzhou, where his community grew to some two thousand. Around 1141 he was accused of talking politics with Zhang Jiucheng, an official whose faction opposed the chief minister Qin Gui, and he was stripped of his robe and banished, first to Hengzhou in Hunan and later farther south to Guangdong, where an epidemic killed many of the monks who had followed him. His students reached him by letter. His disciple Yunwen later compiled his record, the Dahui Pujue chanshi yulu, and of everything in it the letters to officials and their families travelled furthest. In one he wrote that leading seventeen hundred monks at Jingshan and living under supervision in exile had been the same to him.
After Qin Gui's death in 1155 Dahui was pardoned and, on Hongzhi's recommendation, became abbot of the Ayuwang monastery. In 1157 Hongzhi, dying, wrote asking him to take charge of Tiantong. He returned to Jingshan before his death in 1163. Later accounts say he had the printing blocks of his teacher's Blue Cliff Record destroyed, so that students would stop studying kōans as literature.
The letters circulated as a book of their own across East Asia. In Korea, a generation after Dahui's death, Chinul, the founder of the Sŏn school's Chogye tradition, took up phrase-watching from the master's record. In Japan his method shaped kōan practice in the Rinzai school, and Hakuin Ekaku, the eighteenth-century reformer of Rinzai Zen, praised his attacks on silent illumination.