In the link provided by David:
Tamahaṃ bhagavantaṃ abhipūjayāmi (I chant my praise to the Blessed One)
Tamahaṃ bhagavantaṃ sirasā namāmi (I bow my head to the Blessed One)
I believe tamahaṃ may be a compound of ta, a demonstrative base, and maha, declined in the third person accusative in agreement with bhagavantaṃ. If that's the case, "tamahaṃ bhagavantaṃ" may be translated as "to the great/worthy (tamahaṃ) blessed one (bhagavantaṃ)". Would that translation accord with the OP's chant?
But, of course, see a proper pali scholar for a proper translation.