Numbers 28:16,17 - Ellicott's Commentary On The Whole Bible

And in the fourteenth day of the first month... — The observance of the Passover had been in abeyance for thirty-eight years. The law is now promulgated afresh. The observance of the first and seventh days of the feast are enjoined in Exodus 12:16 and Leviticus 23:7-8; and in the latter place it is enjoined that an offering made by fire should be offered for seven days. The nature of that offering is stated in the 19th verse of this chapter, and the fact that the details are not found in Leviticus 23 may be adduced in proof of the prospective character of much of the Levitical legislation.