John Gill 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)

Turn again, and tell Hezekiah the captain of my people,.... The king of them, as the Targum:

thus saith the Lord God of David your father, I have heard your prayer, I have seen your tears; See Gill on "Isaiah 38:5"

behold, I will heal you; instantly, miraculously; and none but God could heal him, his disease being in its kind mortal, and he had been told from the Lord that he should die:

on the third day you shall go up unto the house of the Lord: the temple, to give thanks for his recovery; and this he should do on the third day from thence; so soon should he be well, which would show the cure to be miraculous.