tnHeb “of hewn stones.” Gesenius classifies this as an adverbial accusative—“you shall not build them (the stones of the altar) as hewn stones.” The remoter accusative is in apposition to the nearer (GKC372§117.kk).
65
tn The verb is a preterite with vav (ו) consecutive. It forms the apodosis in a conditional clause: “if you lift up your tool on it … you have defiled it.”