Question

“From where do we derive these eighteen? As it is written: ‘And sons were born to David in Hebron; his firstborn was Amnon, by Ahinoam the Jezreelitess; and his second, Chileab, by Abigail the wife of Nabal the Carmelite; and the third, Absalom son of Maacah … and the fourth, Adonijah son of Haggith; and the fifth, Shephatiah son of Abital; and the sixth, Ithream, by Eglah, David’s wife. These were born to David in Hebron.’ And the prophet said to him: ‘And if that were too little, I would add to you such and such.’ ‘Such’ — six; ‘and such’ — six; making eighteen in total. Ravina challenged this: say rather, ‘such’ — twelve; ‘and such’ — twenty-four. It was also taught in a baraita likewise: ‘He shall not multiply wives for himself’ — more than twenty-four. According to the one who expounds the vav, it would be forty-eight. It was also taught in a baraita likewise: ‘He shall not multiply wives for himself’ — more than forty-eight.”
I brought part of a passage from tractate Sanhedrin in order to ask what you think about derashot. How do you understand this? Do you think that, logically, they really intended to identify the source for “he shall not multiply wives for himself”? Did the Sages themselves think they were really pinpointing the source in the Torah? Because on the face of it, these seem like very far-fetched arguments…
If you have an article on this, I’d be happy to see it.
Thank you very much.