AVŚ 6.122.4
यज्ञम् यन्तं मनसा बृहन्तम् अन्वारोहामि तपसा सयोनिः । उपहूता अग्ने जरसः परस्तात् तृतीये नाके सधमादं मदेम ॥४॥
yajñam yantaṃ manasā bṛhantam anvārohāmi tapasā sayoniḥ | upahūtā agne jarasaḥ parastāt tṛtīye nāke sadhamādaṃ madema ||4||
Devanagari rendered by HREEM from the edition's roman (IAST) text; the IAST is the edition's own.
The great sacrifice, as it goes, with mind, I ascend after, with fervor (? tápas), of like origin; being called upon, O Agni, may we, beyond old age, revel in joint reveling in the third firmament.
Translated by William Dwight Whitney (1905)