Prophets are clearly evident in Mesopotamia from the first centuries of the 2d millennium B.C. They are mentioned in texts from Emar, Egypt, and Aram, as well as from Assyria during the Old Testament period. In Assyria, prophets appear to have been closely associated with the court, delivering oracles regarding the prospects of foreign policies.
The phenomenon of prophetic speech is also present in Israel from the monarchical era to the post-exilic era. Court prophets (e.g., Nathan), as well as unofficial prophets (e.g., Amos) are attested. Not all the prophets of Israel left deposits of oracles. The most extensive of the collections are found in the books of Isaiah, Jeremiah, and Ezekiel. The title of prophet is also accorded to others of varying importance, e.g., Abraham, Moses, Elijah, Elisha, Nathan, and Jehu. Certain of their divine mission to purify Israel's religion, the prophets attacked many aspects of people's lives and came forward as the advocates of the poor and oppressed and as the leaders in social reform. According to them, Israel could be reconciled with God only by complete purification in religion and in the state. It is part of traditional Christian belief, found in the Nicene Creed and Second Peter, that the Holy Spirit "spoke through the prophets" concerning the intentions of God for his people.