Yan manasaa na manute yenaahur mano matam
tad eva brahma tvam viddhi nedam yad idam upasate
"That which cannot be thought of by the mind' - yan manasaa na manute. The mind cannot think of it but because of it, the mind acquires the capacity to think.
Tad eva Brahma tvam viddhi - "That alone is the "Truth,' the Brahman.' Nedam yad idam upaasate - 'nothing that you worship here, nothing that you adore here'. When we say,' I adore something' or ' I worship something,' three things are involved - the worshipper, the worshipped and the act of worship. If anyone looking for the 'Supreme, Unconditioned Self,' the Brahman, then these three separate entities are not required.
Now, please understand that the Upanishad is not saying,'Don't worship,'! Worship is indeed required with a different level of understanding. Even Shankaracharya, after having written commentaries on the Upanishads, established temples because they were necessary for another level of understanding. Everyone cannot start swimming in the ocean right away, but have to be led to that stage gradually, in steps. But when one begin to seriously understand the 'Supreme Truth', these intermediate steps are not important. This is very significant. So it is said, "That which the mind cannot understand, grasp or express, but because of which the mind exists, "That' alone is the "Truth', please understand, nothing that you adore here!'
yat praanena na praaniti yena praanah praniyate
tad eva brahma tvam viddhi nedam yad idam upaasate.
'That which is not breathed by life, but, by which life breathes.' It is the origin of all life. "That alone is the Supreme Brahman, know this, nothing that you adore or worship here!'
Reference - Kenopanishad by Sri M.