The curse for not keeping the law
Paul quotes the curse spoken in Deuteronomy for anyone who does not keep all the words of the law.
All who rely on works of the law are under a curse. For it is written: “Cursed is everyone who does not continue to do everything written in the Book of the Law.”
Deuteronomy 27:26 places under a curse the person who does not put the law into practice. Galatians 3:10 introduces the same warning with, "For it is written."