Charles Ellicott Commentary 2 Kings 20:5

"Turn back, and say to Hezekiah the prince of my people, Thus saith Jehovah, the God of David thy father, I have heard thy prayer, I have seen thy tears: behold, I will heal thee; on the third day thou shalt go up unto the house of Jehovah." — 2 Kings 20:5 (ASV)

The captain of my people. —Or, ruler (nâgîd); a designation of honour (1 Kings 1:35; 1 Samuel 10:1). This is missing in Isaiah 38:0, as well as the end of the verse I will heal thee, etc. That narrative looks like an abbreviated transcript of the present account, or of a common original.

On the third day. —Compare Hosea 6:2. Here, however, there is no ground for understanding the expression other than literally. The precise nature of Hezekiah’s malady cannot be ascertained.