Aitareyabrahmana 3.2.p10

3.2.p10

iii. 16 (xii. 5). When Indra had slain Vṛtra all the deities left him, thinking 'He has not laid (him) low'; the Maruts only, his true comrades, did not leave; the Maruts, true comrades, are the breaths; the breaths did not then leave him. Therefore this unchanging Pragātha containing (the word) 'true friend' is recited, 'Hither, O true friend, with true friends.' Even if here onwards a recitation to Indra is recited, the whole is the Marutvatīya, if this unchanging Pragātha is recited, containing (the word) 'true friend', 'Hither, O true friend, with true friends.'