The Hua Hu Ching is a lesser known collection of the oral teaching of Lao Tzu of Tao te Ching fame. The version I have is translated by Brian Walker. It is short, excellent, and in my opinion a worthy part of every Mahayana Buddhist library.

It is Taoist in the sense there is no reference to Buddhism at all. It is Buddhist in that the content is clearly in alignment with important aspects of Cha’an and Zen Buddhism and their derivatives.