In the Zhuangzi, Confucius teaches Yan Hui the fasting of the heart: listen not with the ears but with the heart, then not with the heart but with qi, which is empty and waits on things. The Dao gathers in emptiness, and emptiness is the fasting of the heart.
Fasting of the heart
Xinzhai: the Zhuangzi’s inner discipline of emptying the mind so that the Dao can gather there.
Also: xin zhai, fasting of the mind