Refers to the monotheistic religion of the Jewish people, central to which is the belief that the ancient Israelites experienced God's presence in human events. Jews believe that the one God delivered the Israelites out of bondage in Egypt, revealed the structure of communal and individual life to them, and chose them to be a holy nation of people able to set an example for all humankind. The Hebrew Bible and Talmud are the two primary sources for Judaism's spiritual and ethical principles. The religion, which traces its origins to Abraham, places more emphasis on expressing beliefs through ritual rather than through abstract doctrine. The Sabbath, beginning on sunset on Friday and ending at sunset on Saturday, is the central religious observance; there is also an annual cycle of religious festivals and days of fasting. Judaism has had a diverse history of development over almost 4000 years, with a number of resulting branches in modern times, namely Orthodox, Conservative, and Reform.