The numbering of the psalms and the verses differs from one Bible to the next and I don't make it easier by using only one Bible, ha. That is why I always type the text in here on the blog rather than just cite a passage and have you look it up, since often the numbering or the translation varies.
This one line from David's famous psalm of repentance is an example of how people can take one line from the Bible and use it as a prayer to God. Those of you who are going through some sort of personal reformation might find this one line to be a very helpful prayer to God as you make progress in your inner work.
Psalm 50 (51): 12
A clean heart create for me, O God, and a steadfast spirit renew within me.