Here’s an interesting portion of the Book of Gad who was a contemporary of Nathan and was a major prophet to David. This excerpt is taken from Ken Johnsons commentary on the book and is available thru Amazon. This book is a source document for many ideas found in scripture like a new Jerusalem and face to face etc. The only earlier mention I’m aware of re the day when the sons of God gather is in Job. Dates, chapter headings and blocks are Kens commentary.
14. The Great Tribulation Rosh Hashanah 2926 AM, 999 BC
1And it came to pass on the first day of the seventh month, at New Year’s, in the four hundred and seventy-eighth year after the children of Israel came out of the land of Egypt, in the second year of King Solomon’s reign over Israel, I had a vision from the LORD, when I was upon the Gihon spring [south of the city of David] 2And I raised my eyes, and lo, the heavens rolled back like a scroll, and I saw the glory of the LORD, sitting on an extremely high throne. 3And here is the appearance of the throne: twelve stairs led up to the throne (six of gold and six of silver), and there was a square back to the throne, like a sapphire stone. 4And at its right side were three chairs and at its left side were four chairs near the throne, like the seven[ xl] that see the king’s face, covered with gold and silver and precious stones. 5And the glory of the LORD had the appearance like that of the rainbow, His covenant. 6And the host of heaven were standing before Him on His right hand and on His left, and Satan was standing by them, but behind them. The Books 7And then a man dressed in linen brought before the glory of the LORD three books that contained the records of every man. 8And he read the first book and it contained the just deeds of His people, and the LORD said, “These are granted eternal life.” 9And Satan said, “Who are these guilty people?” And the man dressed in linen cried to Satan like a ram’s horn saying, “Silence! This day is holy to our Lord.” 10And he read the second book, and it contained the unintentional sins of His people, and the LORD said, “Put that book aside, but save it, until one third of the month passes by, to see what they will do.” 11And he read the third book, and it contained the wicked deeds of His people. 12And the LORD said to Satan, “These are your share. Take them and do what you want with them.” 13And Satan took the wicked to a waste land to destroy them there. 14And the man dressed in linen cried like a ram’s horn, saying: 15“ Blessed are the people who know the joyful shout [who look toward the Rapture], O LORD, who walk in the light of Your countenance.”