This expression reminds us of the words of Joshua (Joshua 23:14) as he faced the end. Death shows no partiality. The greatest heroes of earth take their place with the lowliest of men and both go together to a common grave. Worldly distinctions are only for a moment, and the glories of kings disappear wherever death holds sway.
Be thou strong.
David’s thoughts are not of himself but of his son, not of the past but of the future. He speaks as a loving father, a soldier and patriot, and above all as a man who has shown himself every whit a king. He charges Solomon to be strong as he undertakes the responsibilities of leadership, even as Moses charged Joshua (Deut. 31:7), and as the Lord Himself had charged Joshua (Joshua 1:7).
Shew thyself a man.
In spite of his youth, Solomon now was king, and particularly as such he must show himself a man. He was to be a man in full control of himself and of his people, fearless, above bribery and corruption. He was to seek first, not his own interests, but those of the people whom he had been appointed to serve and of the God whose representative he was.