yadah

This is the plain, physical sense of the word: to send something out of the hand. It covers throwing a stone at someone, hurling a thing down so it loses its standing, and shooting arrows at a target.

It is rare in the Bible, surviving in only a handful of places, and it is almost certainly the older, concrete root behind the far more common worship word. Many scholars connect the two by the picture of the hand: thanksgiving and confession were marked by raised or extended hands, and the same word that meant throwing the hand out came to mean acknowledging God or one's sin out loud. Whether or not that link is exact, in the worship passages the physical action has dropped away entirely, so the two are best treated as separate words.

This is the great worship word of the Old Testament. At its heart it means to say out loud, in public and toward God, what is true. When what is true is God's goodness and rescue, the word means to thank and praise him. When what is true is one's own sin, the same word means to confess it. The two are one act seen from two sides: open acknowledgment of God.

The thanksgiving sense fills the Psalms and the worship of the temple. The repeated call hodu la-YHWH, "give thanks to the LORD, for he is good," is its signature line, and the related noun todah names both the thank offering and the song that went with it. This is not private gratitude but declared praise, often sung with instruments and before a congregation, recounting what God has done.

The confession sense runs through the law and the great prayers of repentance. To confess is to bring sin into the open before God rather than cover it, naming it as the people did over the scapegoat or as Daniel and Nehemiah did on behalf of the nation. The same honesty that praises God for his acts owns the truth about oneself.