Charles Spurgeon Commentary 2 Samuel 7:16-18

"And thy house and thy kingdom shall be made sure for ever before thee: thy throne shall be established for ever. According to all these words, and according to all this vision, so did Nathan speak unto David. Then David the king went in, and sat before Jehovah; and he said, Who am I, O Lord Jehovah, and what is my house, that thou hast brought me thus far?" — 2 Samuel 7:16-18 (ASV)

And your house and your kingdom shall be established for ever before you: your throne shall be established for ever. According to all these words, and according to all this vision, so did Nathan speak to David. Then went king David in, and sat before the LORD,–

Like one weighted down with a great load of mercy, too heavy for him to stand up under it, and therefore he needed to sit down, and consider, and meditate upon the wonderful words of God to him.