A First Course in Probability, Sheldon M. Ross, 2019 (Pearson) - A fundamental textbook for introductory probability, offering a clear and detailed explanation of conditional probability and Bayes' Theorem.
Pattern Recognition and Machine Learning, Christopher M. Bishop, 2006 (Springer) - An essential machine learning textbook that covers the theoretical foundations of Bayesian methods and their applications, including Naive Bayes classifiers.