4:13 Behind - Within the walls where they were not yet raised to their due height, and therefore most liable to the enemies assault. Higher - Upon the tops of the walls where they were finished, and the towers which were built here and there upon the wall; whence they might shoot arrows, or throw stones.
4:7-15 The hindering good work is what bad men aim at, and promise themselves success in; but good work is God's work, and it shall prosper. God has many ways of bringing to light, and so of bringing to nought, the devices and designs of his church's enemies. If our enemies cannot frighten us from duty, or deceive us into sin, they cannot hurt us. Nehemiah put himself and his cause under the Divine protection. It was the way of this good man, and should be our way. All his cares, all his griefs, all his fears, he spread before God. Before he used any means, he made his prayer to God. Having prayed, he set a watch against the enemy. If we think to secure ourselves by prayer, without watchfulness, we are slothful, and tempt God; if by watchfulness, without prayer, we are proud, and slight God: either way, we forfeit his protection. God's care of our safety, should engage and encourage us to go on with vigour in our duty. As soon as a danger is over, let us return to our work, and trust God another time.