The Manduk Upanishads are the most direct, most powerful. They tell you that one consciousness is the absolute reality of this universe. And the silence after Om represents this consciousness. Among all rituals, I am actually the ritual of repeating God's name. This is called Japayagya and it was stressed by Sri Ramakrishna to her disciples.
In this series of talks, Swami Sarvapriyananda unfolds the highest truths of Vedanta through the study of the Bhagavad Gita (The Song of God).