After the promise of healing and the subsequent healing process initiated King Hezekiah still goes on to ask for a sign
2 Kings 20:1-8 NASB
In those days Hezekiah became [a]mortally ill. And Isaiah the prophet the son of Amoz came to him and said to him, “Thus says the Lord, ‘Set your house in order, for you shall die and not live.8 Now Hezekiah said to Isaiah, “What will be the sign that the Lord will heal me, and that I shall go up to the house of the Lord the third day?”
But years later when the scribes and Pharisees request a sign during the time of Christ they were heavily censured for that
Matthew 12:38-39 NASB
38 Then some of the scribes and Pharisees said to Him, “Teacher, we want to see a [ak]sign from You.” 39 But He answered and said to them, “An evil and adulterous generation craves for a [al]sign; and yet no [am]sign will be given to it but the [an]sign of Jonah the prophet;
Why is Hezekiah not rebuked for this seemingly lack of faith?