The Word of Yahweh (Heb: דְבַר־יְהוָה) is His direct communication with His people, especially with his prophets. For this reason, Jewish tradition calls the books following the Torah the “former” prophets.
The Word was passed down by the spoken word (“according to mouth”, Heb: עַל־פִּי) and written finally by Moses when he heard Yahweh speak. Though the words of God were recorded from the beginning the first time the debar-Yahweh is mentioned was to Abram when Yahweh confirmed his promise to him. The fact that debar is recorded is reflected in the primary meaning of the verb form: “to arrange”. It is used of words and things such as events (“After these things [dabarim] the Word [debar]...”). The earlier words spoken to Adam, Cain and Noah, though significant, were not designated the same way.
Those Who Heard the Word of Yahweh
Besides Abraham and Moses in the Torah, over 25 others received the Word directly from the LORD. In the books following, designated “the Former Prophets” by the Jews, a series of God's spokesmen were instructed to do His bidding or to tell His people what He wanted of them. There were Joshua, Samuel, Nathan, Gad, Solomon, Isaiah and Jeremiah, along with some others.
Each of the “Latter Prophets” – Isaiah, Jeremiah, Ezekiel and the Twelve (or Minor) prophets – received their message directly as the Word of Yahweh.