הֹוָ֤ה עַל־הֹוָה֙ תָּב֔וֹא וּשְׁמֻעָ֥ה אֶל־שְׁמוּעָ֖ה תִּֽהְיֶ֑ה וּבִקְשׁ֤וּ חָזוֹן֙ מִנָּבִ֔יא וְתוֹרָה֙ תֹּאבַ֣ד מִכֹּהֵ֔ן וְעֵצָ֖ה מִזְּקֵנִֽים׃
災禍接連臨到，噩耗接踵而來；他們必向先知求異象，卻求不著；祭司失去了律法的教導，長老也失去了謀略。
Rashi
Happening upon happening Heb. הוָֹה עַל-הוָֹה, happening upon happening, being after being. Menachem (p. 70) associated it to a term for a breach.
Rashi
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.”