could somebody give me the grammatically correct version of the mantra "Amitabha Buddha Namah" in Sanskrit? Since "Om namo bhagavate Vasudevaya" has the words being in a declension, I suppose the same is required for the Amitabha mantra too.
The first two are correct. Can't say anything about the third, perhaps a tantric usage. Om Hreem Creem Phat, whatever. IMHO, these are sounds to which our stone-age ancestors danced around the fire along with beating of tree trunks, and considered holy even in this age. Simple, one who does not know 'Beeja mantras' cannot dance. Beeja mantras: