MN 149 Mahā Saḷāyatanika Sutta: The Great Sixfold Base

In an exposition of how to practice non-attachment to the six sense bases, the Buddha says that for one who is practice rightly “These two things, tranquility and insight, occur in him yoked evenly together”.

This evenness of serenity and insight is what is emphasised so much in Chan practice as ‘Silent Illumination’.

Full text