How do we know that prayer to saints is incorrect?

In Luke 16:24, the rich man in hell prays to Abraham for mercy, marking the first and only instance of praying to a saint in Scripture. Throughout the Bible, believers are consistently directed to pray to God alone, as seen in passages like Genesis 4:26 and Matthew 6:9. The lack of any biblical precedent for praying to saints indicates that such practices, which stem from human tradition, lack scriptural support. This understanding aligns with the historic Reformed belief that Christ is our sole mediator, and prayer should be directed to the Father through Him.