Guru Dakshina (Teachers’ contribution) 

एकमेवाक्षरं यस्तु गुरुः शिष्यं प्रबोधयेत्।
पृथिव्यां नास्ति तद्रव्यं यद् दत्त्वा चाऽनृणी भवेत्।। (Chanakya Neeti 15.2)

Any person who teaches a single letter becomes a Guru and there is no treasure in this world which can liberate us from the debt to such a Guru. – Chanakya Neeti 15.2

Lord Krishna, as Gurudakshina, brought back his Guru’s son who was killed by an asura named Panchajana.

Ekalavya gave away his right thumb to Dronacharya as Gurudakshina.

By serving Adi Shankaracharya, his disciple Giri rose to become Totakacharya.