It is well known that Upanishads contain Vedantic statements, but I want to know Vedantic statement from Karma Kanda of Vedas if any.
There are many verses in the Samhitā portion of Vedas that have the same message as the Upanishads. In fact, the Samhitā mantras are seeds for the later elaboration in Upanishads.
Rig Veda 3.26.7 (rishi Vishvāmitra):
अग्निरस्मि जन्मना जातवेदाः घृतं मे चक्षुरमृतं म आसन् ।
अर्कस्त्रिधातू रजसो विमानो अजस्रो घर्मो हविरस्मि नाम ॥
I am Agni, by birth omniscient, Light is my eye and Immortality is my mouth. I am the three-fold sun measuring out the universe, I am both immortal energy and matter.
This is a paraphrasing of "I am Brahman" (aham brahmāsmi). And Sāyaṇācārya gives it a full Vedānta treatment in his commentary.
Rig Veda 6.9: This entire suktam of rishi Bharadvāja is a very candid expression of his enlightenment and vision of deep truth of sat-cid-ānanda. A detailed translation and commentary of this suktam can be found here:
Rig Veda 10.5.7 (rishi Trita Āptya):
असच्च सच्च परमे व्योमन्दक्षस्य जन्मन्नदितेरुपस्थे ।
अग्निर्ह नः प्रथमजा ऋतस्य पूर्व आयुनि वृषभश्च धेनुः ॥
Both non-existence and existence in the highest plane, Daksha's birth in Aditi's womb. Agni is for us the first principle of manifestation, being before creation both bull and cow.
This mantra clearly describes Agni as Brahman, as the reconciliation of opposites, both "this" and "that". Agni is said to be both non-existence and existence. In other words, he is everything (saguṇa) and nothing (nirguṇa).
Rig Veda 5.81.1 (rishi Shyāvāshva Ātreya):
युञ्जते मन उत युञ्जते धियो विप्रा विप्रस्य बृहतो विपश्चितः ।
The wise ones join their mind and intellect with the omniscient Big Wise One.
This mantra pretty much summarizes Yoga, Advaita and Vishishtādvaita. The wise rishis merge their individual self into the universal Self ("Big Wise One"). This is very interesting. First of all, this mantra describes the process of yogic samādhi. The wise persons (rishis) are trying to merge their consciousness and states of being into the universal consciousness.
Second important point to note is that both the humans and the deity are called “wise”. So there is no essential difference in substance between the human aspirant and the divine. The only difference is that the deity is called the “bigger wise”. So in calling them both “wise”, we see the concept of non-duality (advaita). And in calling the deity the “bigger wise”, we see hints of the concept of qualified non-duality (vishishtādvaita).
Rig Veda 5.46.1 (rishi Pratikshatra Ātreya):
हयो न विद्वान् अयुजि स्वयं धुरि तां वहामि प्रतरणीमवस्युवम्।
नास्या वश्मि विमुचं नावृतं पुनर्विद्वान् पथः पुरएत ऋजु नेषति ॥
Like a knowing horse, I have joined myself to the “world cycle” and I carry that which is protective and gives salvation. I do not desire a release from this, nor do I desire a continuation. The wise, all-knowing Atman, knower of the path, the leader will lead me straight.
So this mantra is the seed idea for Karma Yoga, i.e. selfless action. It also has hints of the idea of Bhakti without any selfish desires, and "sharaṇāgati" or "prapatti".
Rig Veda 10.73.11 (rishi Gaurivīti Shāktya):
वयः सुपर्णा उप सेदुरिन्द्रं प्रियमेधा ऋषयो नाधमानाः ।
अप ध्वान्तमूर्णुहि पूर्धि चक्षुर्मुमुग्ध्यस्मान्निधयेव बद्धान् ॥
The rishis, singing beautiful songs, flew to Indra in the form of beautiful birds. They told him, "Remove this darkness, fill us with light and release us from bondage, just as birds are released from their bindings".
So this mantra clearly spells out the desire for release (mokṣa) from darkness or ignorance and desire for the light.
There are many more hidden gems in the Vedas which use very intricate or subtle symbolism to express metaphysical and spiritual truths. In addition, there are at least a dozen mantras that are quoted verbatim in the Upanishads.
Further reading suggestions on my blog: