Charles Ellicott Commentary Haggai 2:14

"Then answered Haggai and said, So is this people, and so is this nation before me, saith Jehovah; and so is every work of their hands; and that which they offer there is unclean." — Haggai 2:14 (ASV)

That which they offer there — i.e., probably, “on that altar,” but the expression is singular. In Ezra 3:3 we read, And they set the altar upon his bases... and they offered burnt offerings thereon unto the Lord, even burnt offerings morning and evening.