"My teacher has said that there are three essentials of Zen practice: cleaning, chanting, and zazen. Just as the story about polishing the tile points out, most of the time we clean with the idea of getting something. We clean so that we can get through with the job and go on to do something more enjoyable, like taking a walk, or something more important,, like sitting down for the next period of zazen or chanting sutras. And then, of course, we find out that the presumed satisfaction in the projected next thing is lacking; that our absent-minded preoccupied cleaning has carried over to the way we take that walk, the way we sit: lackluster.
When we clean with buddha-cleaning-buddha mind, something very different takes place. With this mind, anything---the sound of the drum at lunchtime, pebble hitting a bamboo stalk in the story about Kyogen raking at the National Teacher's grave site, the sudden glimmer of a rainbow in a puddle at our feet--anything can be the trigger that brings us to the sudden recognition of wordless truth. It's never elsewhere. Then we might rephrase the koan: does a buddha have buddha nature or not? Buddha-cleaning- buddha is Mu, nothing more, nothing less. The Book Of Mu, Pg. 218.