Psalms 34:1

לְדָוִד בְּשַׁנּוֹתוֹ אֶת טַעְמוֹ לִפְנֵי אֲבִימֶלֶךְ וַיְגָרְשֵׁהוּ וַיֵּלַךְ

A Psalm of David, when he feigned insanity in front of Avimelech, who drove him away and he departed.

Avimelech? But the account of this story in I Samuel chapter 21 tells us that the king’s name was Achish! Rashi explains that Achich was his given name but “Avimelech” was a generic name for all Philistine kings, the same way that “Pharaoh” was the standard title for all the kings of Egypt. (The Torah discusses other kings called Avimelech in the days of Avraham and Yitzchak.)