The Psalms is called the book of praises, sepher tehillim. Tehillim is defined as “all that is worthy of praise and celebration.” What is worthy of praise? The answer is the pervading theme of the Psalms - the works and ways of the Lord (Jehovah). Psalm 1 sets the pattern of emphasis throughout the whole book.
The man who delights in the Lord and in His Word shall prosper. The problem of the suffering or enduring of the righteous versus the prosperity of the wicked is set at the beginning. The solution is that God always triumphs over all and when a man is cared for by the Lord, he shall prosper and bring forth much fruit.
The praises in the psalms show how God brings deliverance, peace, joy, health and protection to His people. This may be in the form of a song (shir) or meditation (higgaion) or prayer. It is invariably the expression of the magnitude and depth of God working with His people. The thematic content of the Psalms is in essence, personal. It is an I-thee relationship where the believer is describing, imploring, worshipping, magnifying God. The “I” may mean an individual or apply to a whole congregation. It is still basically an individual expression. This personal content means that the psalm is written out of a particular believer's heart and life. It may come out an historical event or situation or out of a moment of enlightened understanding. In either case, it comes from the heart of man to His God and Lord.
There are two words usedfor praise which give a key to understanding the range of personal expression in the Psalms. These two words translated praise are yadah and halal. Yadah means "to confess," literally "to stretch out the hand." The first use in the Bible is in Genesis 29:35. Leah’s fourth child was named Judah, which means “praise the Lord.” The first use of yadah in Psalms gives more insight into the depth of the word.
The standard of what to confess or praise is according to God's righteousness.
Whenever yadah is used, it is in reference to what God has done, either in mighty works or for an individual. It is a description of what God has done. In this sense it comes out of specific situations and is the confession of an individual's heart of what God has done for them. An example of this kind of praise is in Psalm 18:2ff. The Lord is called a rock, a fortress or mountain stronghold, a deliverer, a high tower. It is the confession of David of what God did for him and who God is to him. God is described as "my strength, in whom I will trust."
This confession or praise, yadah, becomes vividly understood because it is linked with thanksgiving. It is translated 37x as thank or give thanks.
The second word for praise is halal and this word incorporates the idea of celebration and rejoicing. We have the transliteration into English in hallelujah. It is praise the Lord with an exclamation point! This word when used often has to do with God's mighty works of creation, his greatness, omnipotence. There are five psalms called the Hallelujah Psalms, 145-150, which begin and end with "praise the Lord."
These two kinds of praise are used together to describe the gamut of expression in the Psalms. They are used together to describe the temple worship services. Here are only several instances where the two words are used together: