Rashi on Zechariah
worthless shepherd a shepherd of nought. אֶלִיל, is an expression of אַל, naught; he is not a shepherd. [There is also] (in Job 13:4) “worthless physicians.” רֹעִי The “yud” is superfluous; it is instead of a “he,” as “who abandons the flock”; (Deut. 33:16) who dwells (שׁכְנִי) in the bramble”; and (Micha 7:14) “who dwells alone.”
Rashi on Zechariah
who abandons the flock Who leaves them free for anyone who comes to beat, to slay, and to spoil.