एकमप्यक्षरं यस्तु गुरुः शिष्यं प्रबोधयेत् । पृथिव्यां नास्ति तद्द्रव्यं यद्दत्त्वा सोऽनृणी भवेत् ॥

There is no treasure on earth the gift of which will cancel the debt a disciple owes his guru for having taught him even a single letter ( that leads to Krishna consciousness)