"The victorious army, returning from the field, approached the city, their shouts of triumph awaking the echoes of the hills. But as they entered the city gate the shout died away, their banners drooped in their hands, and with downcast gaze they advanced more like those who had suffered defeat than like conquerors. For the king was not waiting to bid them welcome, but from the chamber above the gate his wailing cry was heard, “O my son Absalom! my son, my son Absalom! would God I had died for thee, O Absalom, my son, my son!” PP 745.1 “The victory that day was turned into mourning unto all the people; for the people heard say that day how the king was grieved for his son. And the people gat them by stealth that day into the city, as people being ashamed steal away when they flee in battle.” PP 745.2"
"And it was told Joab, Behold, the king weepeth and mourneth for Absalom."
EGW describes the reaction of the people to David's grief, which is directly related to the information given in 2 Samuel 19:1. It's more than just a thematic parallel, as it's a direct continuation of the narrative.
"perceive, that if Absalom had lived, and all we had died this day, then it had pleased thee well. Now therefore arise, go forth, and speak comfortably unto thy servants: for I swear by the Lord, if thou go not forth, there will not tarry one with thee this night: and that will be worse unto thee than all the evil that befell thee from thy youth until now.” PP 745.3"
"In that thou lovest thine enemies, and hatest thy friends. For thou hast declared this day, that thou regardest neither princes nor servants: for this day I perceive, that if Absalom had lived, and all we had died this day, then it had pleased thee well."
EGW directly quotes and attributes the words to Joab, as found in 2 Samuel 19:6.