The four mahavakyas are
1 . प्रज्ञानम् ब्रह्म (Prajñānam brahma) meaning Consciousness is Brahman
from Aitareya Upanishad of Rig Veda
2. अहम् ब्रह्मास्मि (Aham brahmāsmi) meaning I am Brahman
from Brihadāranyaka Upanishad of Yajur Veda
3. तत्त्त्वमसि (Tattvamasi) meaning That thou art from Chhandogya Upanishad of Sama Veda
4. अयमात्मा ब्रह्म (Ayamātmā brahmā) Meaning This Atman is Brahman from Mandukya Upanishad of Atharva Veda
