Śāṅkhāyana (Kauṣītaki) Āraṇyaka 2.9

2.9

ŚĀ 2,9
yā indra bhuja ābhara ityetayā bārhatīm aśītiṃ pratipadyate stotāram in maghavann asya vardhayeti mahadvatyā vṛdhavatyā | mahadvad vṛdhavat | mahadvat - mahadvad dhyetad ahaḥ | ayaṃ te astu haryata ā mandrair indra haribhiḥ sūkte | tad yad ete antataḥ śaṃsati saṃsiddhābhir bṛhatībhir auṣṇihīm aśītiṃ samārohāṇīti ||

ŚĀ 2.9
With [the verse], 'Bring us the advantages, O Indra,' he commences the Bārhata eighty [of verses], [with the words], 'and increase the singer here, O Bounteous One,' which contains [a word meaning] 'great' and [a word meaning] 'increase.' It contains 'great' and contains 'increase.' For great—great indeed is this day. 'May this be dear to thee' [and] 'Come, O Indra, with [thy] delightful bay steeds' are the two hymns. Now, as to why he recites these at the end: [he thinks,] 'Let me ascend to the Auṣṇiha eighty with fully completed Bṛhatī [verses].'