Buddhism is about universal truths and universal moral conduct. They are universal because they transcend belief, race, nationality, and even time and space. The most striking universal truth is that nothing in this world is permanent; everything is subject to change; nothing lasts forever. The generally accepted universal moral conduct are honesty, love, compassion, forgiveness and decent conduct of living.
The Buddha preached these values and he encouraged intelligent analysis of his teachings. He urged his followers to use their common sense and human intelligence to analyze his teachings and only to accept them if the followers found them to be beneficial. His teachings were not from a third or "higher" source. He is called a Buddha for the ability to discern, by himself, the true nature of existence. Since there is no commandment, there is no "holy" book. The teachings of the Buddha are compiled into three groups and are called the Tipitakka, meaning "three baskets". The Tipitakka forms the complete teachings of the Buddha. In this sense you may refer it as the "holy" books. But in the theological sense, there is no "holy book" in Buddhism.