כֹּ֥ה אָמַ֖ר יְהוָ֣ה צְבָא֑וֹת שְׁאַל־נָ֧א אֶת־הַכֹּהֲנִ֛ים תּוֹרָ֖ה לֵאמֹֽר׃
’Thus saith the LORD of hosts: Ask now the priests for instruction, saying:
Rashi on Haggai
Now ask the priests the Torah Perhaps in exile they forgot the laws of sanctified things, and of impurity and purity.