The Lord did not simply encourage Joshua to be strong, but He commanded him to be strong. “Have not I commanded thee?” It was just as much the duty of Joshua to obey this commandment of the Lord as any other, and in obeying it he would be strong. There is all the strength of the Lord’s own life in His commandment. Jesus proved this in His experience, and so He said, “I know that His commandment is life everlasting.” Daniel proved this, and his testimony is, “Then there came again and touched me one like the appearance of a man, and he strengthened me, and said, O man greatly beloved, fear not: peace be unto thee, be strong, yea, be strong. And when he had spoken unto me, I was strengthened, and said, Let my Lord speak; for thou hast strengthened me.” The command to be strong was the means of imparting strength. Obeying the command was the receiving of strength.