Have you ever had a conversation where someone is giving you instructions, and they keep repeating themselves?
Over and over.
Like you didn't get it the first time (or second or third, ad infinitum)
The psalmists do that in the book of Psalms. Though there are different authors, they collectively present one central theme - the steadfast love of the Lord! It is as if the Holy Spirit wants us to get that one thing right by repeating it to us over and over and over again.
Instead of being offended, we should realize that there is a reason for the repetition. We tend to miss the love of the Lord, in all of its aspects, just as many times as it is repeated in the Psalms. We deserve - no, we need - the repetition.
The phrase is found 127 times in Psalms. The root Hebrew word, "hesed" is central to a basic understanding of the character of God. If you miss that central point, you miss the heart of God's Word. God is both holy and sacrifically loving toward you and me.
In this video, Winfree Brisley continues talking about repetition in the Psalms and God's unquenchable love toward us.