Mundaka-2-2-8-bhidyate

Sri Shankara’s Commentary (Bhashya) translated by S. Sitarama Sastri

The fruit of the knowledge of the Paramatman is stated to be the following. Loosened is “the knot of the heart,” i.e., the group of tendencies in the mind due to ignorance, the desire which clings to the intellect according to the Sruti “The desires which lie imbedded in the heart, etc.” This is attached to the heart (intellect) not to the Atman. Biddyate. undergoes destruction; doubts regarding all knowable things have their solution—doubts which perplex worldly men up to their death, being (continuous) like the stream of the Granges; of the man whose doubts have been solved and whose ignorance has been dispelled, such karma as was anterior to the birth of knowledge in this life, such as was performed by him in previous births and had not begun to bear fruit and such as was existing at the birth of knowledge come to an end; but not that karma which brought about this birth, for it had begun to bear fruit. He, “the omniscient”, not subject to samsara; ‘both high and low,’ high as being the cause and low as being the effect; when he is seen directly as “I am he”, one attains emancipation, the cause of samsara being up-rooted.

Links
Various resources on the Mundakopanishad
Upanishad Series – Mundakopanishad Commentary by Swami Chinmayananda