Jamieson, Fausset and Brown on Galatians 3:10

10. Confirmation of Ga 3:9. They who depend on the works of the law cannot share the blessing, for they are under the curse "written," De 27:26, Septuagint. Perfect obedience is required by the words, "in all things." Continual obedience by the word, "continueth." No man renders this obedience (compare Ro 3:19, 20). It is observable, Paul quotes Scripture to the Jews who were conversant with it, as in Epistle to the Hebrews, as said or spoken; but to the Gentiles, as written. So Matthew, writing for Jews, quotes it as "said," or "spoken"; Mark and Luke, writing for Gentiles, as "written" (Mt 1:22; Mr 1:2; Lu 2:22, 23) [Townson].