Katha-2-3-8-avyaktāttu

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

Beyond the Avyaktam is Purusha all-pervad-ing, being the cause of all âkâsa, etc., which is all-pervading. Devoid of linga ] that by which anything is reached (known) is linga such as intellect, etc. That does not exist in him; so he is devoid of linga. The meaning in effect is devoid of all the attributes of samsâra. Him knowing, both from the preceptor and the sâstrâs, the mortal, even during life, is freed from the knots of the heart, such as ignorance, etc., and even when the body falls, attains immortality. This clause is connected with the previous one thus. He is the Purusha beyond the Avyaktam, etc.

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