TSK · Numbers 9:11

They will eat the meat the same night; they will eat it roasted over the fire with bread made without yeast and with bitter herbs.

In the fourteenth day of this month, at twilight, you are to observe it at its appointed time; you must keep it in accordance with all its statutes and all its customs.”

The king, his officials, and the entire assembly in Jerusalem decided to observe the Passover in the second month.