Adi Shankara's stand

Sri Adi Shankaracharya who propounded the Advaita philosophy his whole life echoed the instructions of Lord Krishna's in his Gita Mahatmya (glorification of the Gita). Therein he states:

ekam shastram devaki-putra-gitam
eko devo devaki-putra eva
eko mantras tasya namani yani
karmapy ekam tasya devasya seva

Let there be one scripture, the Gita spoken by Lord Krishna; let there be one deva, the son of Devaki; let there be one mantra, the name of Lord Krishna; and let there be one work, service to Bhagavan Sri Krishna.

Bhajagovindam from Adi Shankaracharya

Bhagavath Gita Kinchita Theertha
Ganga Jalalapi Kanika Peetha
Sakruthapi Yena Murari Samaracha
Kriyathe Thasyaya Menana Charcha!
Bhaja Govindam Bhaja Govindam Govindam Bhaja Moodamathe!

To one who has studied the Bhagavad Gita even a little, who has sipped at least a drop of Ganges-water, who has worshipped at least one Lord Muraari, to him there is no quarrel with Yama, the Lord of Death.

Although his philosophy is one of covered atheism, he glorifies Krishna as the Supreme Personality of Godhead and that it is the prime duty of every individual being to take up bhaki to Krishna. So he sings Bhaja Govindam Bhaja Govindam Bhaja Govindam three times just to show it as truth beyond any grain of doubt. Therefore chanting Krishna's Holy names (Hare Krishna maha mantra) is the essence of the entire Vedas and its conclusions (Vedanta).

Hare Krishna