Here is where our name "YADAH" (emphasis on second syllable) comes from:

2 Chronicles 20:19-21 Then the Levites of the children of the Kohathites and of the children of the Korahites stood up to praise the LORD God of Israel with voices loud and high. So they rose early in the morning and went out into the Wilderness of Tekoa; and as they went out, Jehoshaphat stood and said, “Hear me, O Judah and you inhabitants of Jerusalem: Believe in the LORD your God, and you shall be established; believe His prophets, and you shall prosper.” And when he had consulted with the people, he appointed those who should sing to the LORD, and who should praise the beauty of holiness, as they went out before the army and were saying: “Praise the LORD, For His mercy [endures] forever.” The Hebrew word that we are very familiar with for “Praise the Lord” is Hallelujah. The word for praise used is Halel. But, the word for praise used in the above verse is “Yadah” which means to let God be known in public, to tell others what God has done. Its root meaning is to “throw out the hand.” So, Jehoshaphat put his choir on the front line for battle and the song they chose to sing went something like this – “Tell everyone what God has done! Let it be known His great works, for His mercy will last forever!” How effective was the song? When they got to the enemy's camp, every enemy was dead. They did not raise a sword but they raised a praise!

(from http://wordnuggets.wordpress.com/2009/09/09/yadah-praise/ )