John Gill, on Isa 38:12

I reckoned till morning,.... Or, "I set my time till the morning (m)"; he fixed and settled it in his mind that he could live no longer than to the morning, if he lived so long; he thought he should have died before the night came on, and, now it was come, the utmost he could propose to himself was to live till morning; that was the longest time he could reckon of. According to the accents, it should be rendered, "I reckoned till morning as a lion"; or "I am like until the morning as a lion"; or, "I likened until the morning (God) as a lion"; I compared him to one; which agrees with what follows. The Targum is, "I roared until morning, as a lion roars;'' through the force of the disease, and the pain he was in: or rather, "I laid my bones together until the morning as a lion; "so indeed as a lion God" hath broken all my bones (n):'' so will he break all my bones; or, "it will break"; that is, the sickness, as Kimchi and Jarchi; it lay in his bones, and so violent was the pain, that he thought all his bones were breaking in pieces; such is the case in burning fevers, as Jerom observes; so Kimchi interprets it of a burning fever, which is like a fire in the bones. Some understand this of God himself, to which our version directs, who may be said to do this by the disease: compare with this Job 16:14 and to this sense the following clause inclines: from day even tonight wilt thou make an end of me; he lived till morning, which was more than he expected, and was the longest time he could set himself; and now be reckoned that before night it would be all over with him as to this world. This was the second day of his illness; and the third day he recovered, and went to the temple with his song of praise. (m) "statui, vel posui usque ad mane", Pagninus, Montanus; "constitui rursum terminum usque mane", Vatablus. (n) Reinbeck de Accent Heb. p. 411.