The Taittiriya Upanishad constitutes the Seventh, Eighth, and Ninth Vallis (sections) of the Taittiriya Aranyaka of the Yajur Veda. The last of these is known as the Bhrigu Valli, and here is how it ends:
He who knows this, when he has departed this world, after reaching and comprehending the Self which consists of food, the Self which consists of breath, the Self which consists of mind, the Self which consists of understanding, the Self which consists of bliss, enters and takes possession of these worlds, and having as much food as he likes, and assuming as many forms as he likes, he sits down singing this Sâman (of Brahman): "Hâvu, hâvu, hâvu! I am food (object), I am food, I am food! I am the eater of food (subject), I am the eater of food, I am the eater of food! I am the poet (who joins the two together), I am the poet, I am the poet! I am the first-born of the Right (rita). Before the Devas I was in the centre of all that is immortal. He who gives me away, he alone preserves me: him who eats food, I eat as food. I overcome the whole world, I, endowed with golden light." This is the Upanishad
For those who don't know, Saman is a term generally used to refer to the hymns of the Sama Veda, which are set to musical melody unlike the hymns of other Vedas. So my question is, is the Taittiriya Upanishad quoting some hymn of the Sama Veda here?
This webpage claims that it is from the Sama Veda, and that it's a hymn that's used by the gods to venerate Vishnu in Vaikuntha:
The Sama Veda is almost entirely musical, and is most pleasing to hear-this Veda is sung and not recited, as is indicated by the usage, “SAma gAnam”. The Taittiriya Upanishad attests to the fact that the Nitya Suris in Sri Vaikuntam please the Lord through melodious singing of SAma mantras- “Etat SAma gAyan AstE”.
And this webpage claims that Parashara Bhattar, a famous Sri Vaishnava Acharya said the same thing:
SrI BhaTTar uses the above interpretation and explains the nAma as "One Who has the mukta-s or the Released souls singing the sAma hymns in praise of Him once they have attained Him" – sva-prApti madhu pAnena "hAvu hAvu hAvu" iti sAmAni gAyamAno muktaH asya asti iti sAma-gAyanaH. He gives the quote from taittirIya Upanishad – "etat sAma gayannAste" – (The released soul or mukta) will be singing this sAma chant.
But at first glance I can't find this hymn in the Sama Veda; you can read the Sama Veda here. If it helps, here is the hymn in Sanskrit:
hā 3 vu hā 3 vu hā 3 vu |
aham̐ ślokakṛdaham̐ ślokakṛdaham̐ ślokakṛt |
ahamasmi prathamajā ṛtā3sya |
pūrvaṃ devebhyo'mṛtasya nā3bhāyi |
yo mā dadāti sa ideva mā3''vāḥ |
ahaṃ viśvaṃ bhuvanamabhyabhavā3m |
suvarna jyotīḥ |
ya evaṃ veda |
It looks like this hymn is also chanted in the famous Tirumala Venkateshwara Temple in Tirupati when giving the Venkateshwara statue an Abhishekha (bath); see this video starting from about the 30 second mark, where the priests are clearly singing it in the style of Sama Veda chanting. That lends some credence to the notion that it's a hymn from the Sama Veda which is chanted in praise of Vishnu in Vaikuntha.
Does anyone know whether this hymn occurs in the Sama Veda, and if so where iin the Sama Veda?