| Barnes' Notes on the Bible Josephus gave Solomon a reign of 80 years, either because he wished to increase the glory of his country's greatest king, or through his having a false reading in his copy of the Septuagint Version. It is, no doubt, remarkable that the three successive kings, Saul, David, and Solomon, should have each reigned forty years Acts 13:21; 2 Samuel 5:4-5; but such numerical coincidences occur from time to time in exact history.
Clarke's Commentary on the BibleSolomon reigned - forty years - Josephus says fourscore years, which is sufficiently absurd. Calmet supposes him to have been eighteen years old when he came to the throne, and that he died A.M. 3029, aged fifty-eight years; and, when we consider the excess in which he lived, and the criminal passions which he must have indulged among his thousand wives, and their idolatrous and impure worship, this life was as long as could be reasonably expected.
Gill's Exposition of the Entire BibleAnd the time that Solomon reigned in Jerusalem, over all Israel, was forty years. The same says Eupolemus (z), an Heathen writer, who makes him to live but fifty two years; which is the common tradition of the Jews, who suppose he was but twelve years of age when he began to reign; which is to be confuted from the age of his son Rehoboam, see 1 Kings 14:21. Josephus (a), on the other hand, makes him to live to too great an age, who says that he reigned eighty years, and lived to ninety four. (z) Apud Euseb. Praepar. Evangel. l. 9. c. 34. (a) Antiqu. l. 8. c. 7. sect. 8.
Geneva Study BibleAnd the time that Solomon reigned in Jerusalem over all Israel was forty years.
Wesley's Notes 11:42 Forty years - His reign was as long as his father's, but not his life; sin shortened his days.
King James Translators' Notestime: Heb. days
Matthew Henry's Concise Commentary11:41-43 Solomon's reign was as long as his father's, but his life was not so. Sin shortened his days. If the world, with all its advantages, could satisfy the soul, and afford real joy, Solomon would have found it so. But he was disappointed in all, and to warn us, has left this record of all earthly enjoyments, Vanity and vexation of spirit. The New Testament declares that one greater than Solomon is come to reign over us, and to possess the throne of his father David. May we not see something of Christ's excellency faintly represented to us in this figure?
Matthew Henry's Whole Bible CommentaryVerses 41-43 We have here the conclusion of Solomon's story, and in it, 1. Reference is had to another history then extant, but (not being divinely inspired) since lost, the Book of the Acts of Solomon, v. 41. Probably this book was written by a chronologer or historiographer, whom Solomon employed to write his annals, out of which the sacred writer extracted what God saw fit to transmit to the church. 2. A summary of the years of his reign (v. 42): He reigned in Jerusalem (not, as his father, part of his time in Hebron and part in Jerusalem), over all Israel (not as his son, and his father in the beginning of his time, over Judah only), forty years. His reign was as long as his father's, but not his life. Sin shortened his days. 3. His death and burial, and his successor, v. 43. (1.) He followed his fathers to the grave, slept with them, and was buried in David's burying-place, with honour no doubt. (2.) His son followed him in the throne. Thus the graves are filling with the generations that go off, and houses are filling with those that are growing up. As the grave cries, "Give, give," so land is never lost for want of an heir. | 
