The metrical version of this psalm is one of the best known psalms in the Psalter. It has been a common song of worship in the Christian church from its beginning – it was often used for morning prayer in the early church.
The psalm is classified as a thanksgiving psalm (v. 4) and some have speculated that it may have been sung when the thank offering was made. It begins with a call to worship in which the singers anticipate worldwide participation (v. 1). Obviously we can use this desire in a greater sense than Israel could because the Christian church is now found throughout the church. It is beneficial to our hearts to remind ourselves of the Lord’s universal power.
The psalmist is addressing the people as they are about to enter the temple courts. He reminds them that the appropriate way of appearing before God is with joy and gladness, and these outlooks are expressed by singing (v. 2). He is the faithful Creator who looks after them as the heavenly Shepherd who provides for their needs and protects them from their enemies (v. 3).
So whenever they join together in worship, they are to be thankful. At the same time, they should be optimistic about the future. Their God will always be good to them, will always love them, and will extend his faithfulness to every generation of his people.