Charles Ellicott Commentary Zechariah 13:1

"In that day there shall be a fountain opened to the house of David and to the inhabitants of Jerusalem, for sin and for uncleanness." — Zechariah 13:1 (ASV)

The meaning of this verse seems to be that the people would keep the law with more heartfelt earnestness, and consequently acceptably. There seems to be a reference to Numbers 8:7; Numbers 19:9 and following.