You know that Lord Buddha was Hindu, born in India, in a royal family, but because He advocated voidism, His philosophy was not accepted by the leaders of Vedic principles. For the time being, Lord Buddha's philosophy was accepted by emperor Asoka, and due to royal influence, it spread all over India. But later on, when Sankaracarya preached the Vedic principle, the voidism of Lord Buddha was driven out of India. Similarly, when Ramanujacarya found Sankaracarya a second edition of Buddhist philosophy, he also expunged Sankaracarya as compromising the Buddha, and he established Personal worship of Lord Visnu.
Letter to Hayagriva, 10 July, 1968