Rashi on the Prophets and Writings

And David said, etc. from now on, anyone seeking the Lord to offer a sacrifice to Him shall go forth and sacrifice on that altar.

to gather the strangers who had converted, because he did not wish to make Israelites perform rigorous labor. And so we find with Solomon below (II Chron. 2:1): “And Solomon counted, etc.”; (ibid. verse 17): “And he made of them seventy thousand who bear burdens.” And it is written further (ibid. 8:7): “And all the people remaining from the Hittites, etc., who were not of Israel, etc.”; (ibid. verse 9): “And of the Children of Israel, whom Solomon did not make slaves, etc.”

for the nails, for the doors of the gates in German, negel, nails.
And David prepared... for the couplings the iron [implements] with which they join and reinforce the doors and the gates.

and the Tyrians with Huram, the king of Tyre.

is young and tender נַעַר, because even one [who is] forty-two years old is called נַעַר, for it is written: (Exod. 33:11): “... and his young (נַעַר) servant, Joshua the son of Nun, did not depart, etc.,” for Joshua reigned after Moses only twenty-eight years, and he lived one hundred and ten years. We find (in the first year that the Israelites were in the desert) that Scripture testifies about him: “and Joshua the son of Nun, his young [servant],” and at that time he was forty-two years old. Therefore, it was necessary to write, “tender,” because he [Solomon] was only twelve years old when he reigned.
magnified on high It was very tall, for Solomon raised it up to one hundred and twenty cubits, as it is written: (I Kings 6:3): “And the porch before the Temple of the House, etc.”