Very know that Brahman is supreme God.
So are there any verse from the vedas that say clearly say Brahman is immortal.
Here are the few verses from Scripture saying Brahman is Immortal
This Purusha who wakes when all sleep, creating what was desired is certainly ‘the pure,’ that is Brahman and that is said to be immortal. All worlds are fastened on that; none passes beyond that. This verily is that.(Katha Upanishad 2.2.8)
Root up and branches down is this ancient asvattha tree, that (its source) is pure. That is Brahman and that alone is called immortal. On that, do all worlds depend and none passes beyond that. This verily is that. (Katha Upanishad 2.3.1)
The purusha alone is all this universe—Karma and Tapas. All this is Brahman, the highest and the immortal; who knows this as seated in the cavity of the heart, unties the knot of ignorance even here, Oh good looking youth! (Mundaka Upanishad 2.1.10)
What is bright, what is smaller than the small, in what are centred all the world and those that live in them is this immortal Brahman. That is prana, that is speech and mind. That is true and immortal; good looking youth. Strike thy mind upon that which should be struck by the mind.(Mundaka Upanishad 2.2.2)
All this before is immortal Brahman; certainly all behind is Brahman; all to the south and to the north; all bellow and all alone stretched out, i.e., extended, all this is certainly Brahman, the highest.(Mundaka Upanishad 2.2.11)