Midrasch zu Könige I 2:45

Rabbi Yitzḥak began: “With the rise of the righteous the people rejoice, and with the rule of the wicked the people sigh.” (Proverbs 29:2). When the righteous achieve prominence, there is joy and happiness in the world; there is joy [va]¹⁰The word king [melekh] is preceded with the prefix vav heh. Va is an expression of joy. in the world: “And the King [vehamelekh] David” (II Samuel 3:31), va that David reigned; “and the King [vehamelekh] Solomon” (I Kings 2:45) va that Solomon reigned; “and the King [vehamelekh] Asa” (I Kings 15:22), va that Asa reigned. This is regarding kings of Israel; from where [do we know] regarding kings of the nations of the world? As it is stated: “And Cyrus the King [vehamelekh]” (Ezra 1:4), va that Cyrus reigned.
But when the wicked achieve prominence, woe [vai],¹¹The word reign [yimlokh] is preceded with the prefix vav yod. Vai is an expression of woe. sighing, and enflamed wrath are in the world. “Ahab son of Omri reigned [vayimlokh] over Israel” (I Kings 16:29), vai that Ahab son of Omri reigned. “Hoshe’a son of Ela…reigned [vayimlokh]” (II Kings 15:30), vai that Hoshe’a son of Ela reigned. “Zedekiah son of Yoshiyahu reigned [vayimlokh]” (Jeremiah 37:1), vai that Zedekiah son of Josiah reigned. Regarding kings of the nations of the world, it is as it is written: “It was [vayhi] during the days of Aḥashverosh” (Esther 1:1), vai that Aḥashverosh reigned.