Hebrews 3:19

So we see. The author concludes the line of thought introduced by the quotation begun in v. 7.

They could not enter. The generation of Israelites whose rebellion reached a climax at Kadesh-barnea was barred from entering the Promised Land because of a fundamental and fatal defect, not by an arbitrary act on the part of God or because Moses had failed to provide strong and able leadership. Moses had been “faithful in all his house” (vs. 2, 5), and could therefore not be charged with responsibility for their failure. Their lack of faith, demonstrated by their disobedience, made it impossible for them to enter.

Unbelief. The “unbelief” of the people stands forth in sharp and sad contrast with the faithfulness of Moses. Had the people been more like him they might have entered in. Like Moses, Christ also is “faithful” and cannot be held responsible for the failure on the part of some Christians to enter into the promised “rest” of soul (see on v. 11). This is the lesson drawn by the author from the experience of ancient Israel (see on Heb. 4:1).