The Vedas are the oldest and most authoritative Hindu scriptures (c. 1500-500 BCE), considered the supreme source of religious knowledge. While Bhagavad Gita, Puranas, and Upanishads are sacred texts, the Vedas (Rig, Yajur, Sama, Atharva) are regarded as the most pious as they are believed to be eternal divine revelations (shruti) rather than human compositions (smriti).