And Hezekiah answered, It is a light thing for the shadow to go down ten degrees: nay, but let the shadow {g} return backward ten degrees.

(g) Let the sun go so many degrees back, that the hours may be fewer in the king's dial.

Wesley's Notes

20:10 Go down - In an instant: for that motion of the sun is natural for the kind of it, though miraculous for the swiftness of it; but the other would be both ways miraculous.

Matthew Henry's Concise Commentary

20:1-11 Hezekiah was sick unto death, in the same year in which the king of Assyria besieged Jerusalem. A warning to prepare for death was brought to Hezekiah by Isaiah. Prayer is one of the best preparations for death, because by it we fetch in strength and grace from God, to enable us to finish well. He wept sorely: some gather from hence that he was unwilling to die; it is in the nature of man to dread the separation of soul and body. There was also something peculiar in Hezekiah's case; he was now in the midst of his usefulness. Let Hezekiah's prayer, see Isa 38. interpret his tears; in that is nothing which is like his having been under that fear of death, which has bondage or torment. Hezekiah's piety made his sick-bed easy. O Lord, remember now; he does not speak as if God needed to be put in mind of any thing by us; nor, as if the reward might be demanded as due; it is Christ's righteousness only that is the purchase of mercy and grace. Hezekiah does not pray, Lord, spare me; but, Lord, remember me; whether I live or die, let me be thine. God always hears the prayers of the broken in heart, and will give health, length of days, and temporal deliverances, as much and as long as is truly good for them. Means were to be used for Hezekiah's recovery; yet, considering to what a height the disease was come, and how suddenly it was checked, the cure was miraculous. It is our duty, when sick, to use such means as are proper to help nature, else we do not trust God, but tempt him. For the confirmation of his faith, the shadow of the sun was carried back, and the light was continued longer than usual, in a miraculous manner. This work of wonder shows the power of God in heaven as well as on earth, the great notice he takes of prayer, and the great favour he bears to his chosen.