Mahavaakya of the Gita

What the great, the supreme word of the Gita is, its mah¯av¯akya, we have not to seek; for the Gita itself declares it in its last utterance, the crowning note of the great diapason.
“With the Lord in thy heart take refuge with all thy being; by His grace thou shalt attain to the supreme peace and the eternal status. So have I expounded to thee a knowledge more secret than that which is hidden. Further hear the most secret, the supreme word that I shall speak to thee. Become my-minded, devoted to Me, to Me do sacrifice and adoration; infallibly, thou shalt come to Me, for dear to me art thou. Abandoning all laws of conduct seek refuge in Me alone. I will release thee from all sin; do not grieve.”

Ref:  Essays on the Gita