nAma japa is the spiritual practice of repeatedly chanting the name of God or a sacred mantra to cultivate focus, devotion, and inner peace.
Yes, concentrated nAma japa of AGNI was mentioned in the Rig Veda.
AGNI does not indicate any physical god, but the formless ENERGY/BRAHMAN.
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अग्नेर्वयं प्रथमस्यामृतानां मनामहे चारु देवस्य नाम । स नो मह्या अदितये पुनर्दात्पितरं च दृशेयं मातरं च ॥
agner vayam prathamasyāmṛtānām manāmahe cāru devasya nāma
| sa no mahyā aditaye punar dāt pitaraṃ ca dṛśeyam mātaraṃ ca ||
English translation:
“Let us do (uninterrupted) recitation (manāmahe) of the auspicious/beautiful name of Agni, the first divinity of the immortals, that he may give us back to the great Aditi, and that I may behold again my father and my mother.”
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If understood in esoteric sense, beholding father and my mother indicates, experiencing the DIVINE BLISS, where one cannot differentiate the Masculine and Feminine energies.
As AGNI is the formless ENERGY/BRAHMAN, recitation of AGNI’s name indicates name of any DIVINITY, ie., Male or Female.