gītā mahātmya - Verse śloka 6
śloka 6
ekam śāstra devakīputra gītā-
meko devo devakīputra evenyū
eko mantrastasya nāmāni yāni
karmapayekaṃ tasya devasya sevā
Translation
There is one science: the Gita taught by Krishna; there is one Bhagavan: Shri Krishna; there is one mantra: His name; and there is one service: the service of Him.