According to one opinion in the Gemara (Bab. Shab. 56b), the reason David's kingdom split was because he sinned by believing Lashon HaRa'. According to another opinion, though, he never sinned at all. ...
Did Yishai sin? The gemarah (shabbat 55b) states pretty clearly that he did not; however, the midrash (Yalkut HaMakiri, cited here) seems to indicate that he separated from his wife for an extended ...