Or HaChaim on Genesis 49:27/אור החיים על בראשית מ״ט:כ״ז

1 בנימין זאב יטרוף, "Benjamin is a wolf that devours its prey, etc." Jacob referred to King Saul who acted like a wolf. It is the nature of the wolf not to remain at the site where he tears its prey. Saul was in a hurry when he failed to wait for the time Samuel had said he should wait (Samuel I 13,8). This became the reason that Saul only ate on the morning (the early part of his reign) and he did not serve out his term.

2When Jacob spoke about ובערב, he referred to the evening of Saul's reign (Samuel I 18,7) when Saul was described as having killed thousands whereas David was credited with having killed tens of thousands. It is also possible that Jacob referred to the division of David's kingdom, which the Talmud Yuma 22 attributes to David having believed Tzivah's accusation against Mefiboshet and disinheriting him partially without checking out the story (Samuel II 19,30). According to the Talmud a heavenly voice proclaimed at that time that Rechavam and Yerovam would divide David's kingdom. This was the beginning of the setting of the sun for Israel (loss of grandeur), because of its sins.