יחזקאל ז:כו פירוש: רש״י

Happening upon happening Heb. הוָֹה עַל-הוָֹה, happening upon happening, being after being. Menachem (p. 70) associated it to a term for a breach.

and instruction will be lost from a priest who usually gave instruction, as is said (Mal. 2:7): “and teaching should be sought from his mouth.”