What is the sutta in which the Buddha described focusing the mind as similar to whittling? I believe there is a sutta in which the Buddha uses an example of whittling or carving a piece of wood to describe the process of refocusing your mind in meditation. What is this sutta?
I am not sure that these are what you asking for.


Maha-Malunkya Sutta: Insight Meditation To Be Anāgāmi-Ariya


http://tipitaka.wikia.com/wiki/Maha-Malunkya_Sutta


Maha Saropama Sutta: The Longer Heartwood-simile Discourse


https://www.accesstoinsight.org/tipitaka/mn/mn.029.than.html


Angulimala Sutta: About Angulimala


https://www.accesstoinsight.org/tipitaka/mn/mn.086.than.html