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.
In that day - connected with the close of Zechariah 12:1-14. The mourning penitents are here comforted.
There shall be a fountain opened. It has been long opened, but then first it shall be so "to the house of David" (representing all Israel), after their long and weary wanderings. Like Hagar in the wilderness, they remain ignorant of the refreshment near them, until God "opens their eyes" (Genesis 21:19). (Moore.) It is not the fountain, but their eyes that need to be opened. It shall be a "fountain" ever flowing: not a laver, needing constantly to be replenished with water, such as stood between the tabernacle and altar (Exodus 30:18).
For sin and for uncleanness - i:e., for judicial guilt and moral impurity. Thus justification and sanctification are implied in this verse as both flowing from the blood of Christ, not from ceremonial sacrifices (1 Corinthians 1:30; Hebrews 9:13-14; 1 John 1:7: cf. Ezekiel 36:25). "Sin" in Hebrew х chaTaa't (H2403), from chaaTaa' (H2398)] is literally a missing the mark or way.