Which is the first book of Jainism?

In Jainism, the earliest and most important scriptures are known as the Agamas. Among the Agamas, the first and most significant is the Ācāranga Sūtra. This text contains the teachings of Lord Mahavira, the 24th Tirthankara, and outlines the code of conduct for ascetics, focusing on non-violence (ahimsa) and discipline. The Ācāranga Sūtra is considered the foundational scripture of the Śvetāmbara sect of Jainism.

It is important to note that the Digambara sect believes the original Agamas have been lost, and they rely on other ancient texts such as the Shatkhandagam and the Kasayapahuda. However, the Ācāranga Sūtra is generally regarded as the first and oldest Jain text.