The fact that in 1 Samuel chapter 16, we read that the Lord sent a “tormenting” spirit to Saul when the spirit of the Lord had withdrawn from him isn’t exactly a good thought to have. BUT maybe, just maybe under this condition Yahweh chose this particular time for a much bigger purpose than anyone at that time could imagine, being the integration of David.
I think it’s interesting that the way in which the “tormenting” spirit could be calmed that was residing inside of king Saul was for a lyre to be played to him to sort of relax him. And when it was commanded for the servants to find an individual who could play the lyre like no other, they found after asking around and searching the future king of kings David. I believe that Yahweh used this precise moment and circumstances to integrate David into the scene with King Saul being that king Saul would find favor in David, whom he did, it was almost like love at first sight.
I also find it somewhat of a “coincidence” that it just so happened David was excellent at playing the lyre, that was used to settle the tormenting spirit that was sent to Saul by the Lord. I personally thought that this raised an interesting discussion simply that there are many ways you could go with this argument and of course many different conclusions you could come to. I even found a web-site that explained how this occasion was the first recorded case of Bi-Polar Disorder. But, upon further thought it made perfect sense that this would happen to Saul. Although Saul had sinned against the Lord, I believe that with this Yahweh used it to his advantage to persuade Israel in the direction he wanted to go, and to integrate who would become the next major character of the Bible and also be directly linked to the coming messiah, David.
If you would like to read the argument that the “tormenting spirit,” that was sent to Saul by Yahweh was one of the first recorded cases of bi-polar, you can check it out here. http://www.examiner.com/article/was-sauls-evil-spirit-a-manifestation-of-current-day-bipolar-disorder