Buddho : The one who knows which is above the mind? A Dhammatalk by Ajahn Chah

In this Dhamma Talk, Venerable Ajahn Chan expound about Buddho the one who knows which is above the mind as quoted below, what is it? is it just part of the mind? I'm looking for further reference on this if possible from the Pali canon... Many Thanks > ... For us it's the same. Only this mind is important. That's why they say to train the mind. Now if the mind is the mind, what are we going to train it with? By having continuous sati and sampajañña we will be able to know the mind. **This one who knows is a step beyond the mind, it is that which knows the state of the mind. The mind is the mind. That which knows the mind as simply mind is the one who knows. It is above the mind. The one who knows is above the mind, and that is how it is able to look after the mind, to teach the mind to know what is right and what is wrong.** In the end everything comes back to this proliferating mind. If the mind is caught up in its proliferations there is no awareness and the practice is fruitless.