Joshua 1:6

6. Be strong and of a good courage [Better, Be strong and firm. Michaelis remarks that the verb חזק , to be strong, denotes strength of hand and arm to lay hold of and retain any thing within one’s grasp; while אמצ , to be firm, denotes rather firmness in the knees, and ability to maintain one’s position against the attack of foes. The expression occurs with increasing emphasis four times in this chapter, and is rather a command than an exhortation. Compare Isaiah 35:3: “Strengthen ye the weak hands, and confirm the feeble knees.”] It is a command as imperative as any in the Decalogue, for strength of will and indomitable firmness must constitute the state of mind out of which all acts of obedience spring.

For unto this people shall thou divide Or, thou shalt cause this people to inherit the land. The Lord would inspire Joshua with strength of soul by disclosing to him the grandeur of his mission. He reveals to him that his agency is the last link in the chain which unites prophecy and fulfilment, hope and fruition: that all the glorious possibilities of his nation hinge upon his own personal valor and fidelity.