They had not been able to celebrate it at the regular time because not enough priests had consecrated1 themselves and the people had not assembled in Jerusalem.
References for 2 Chronicles 30:3
The plan seemed right both to the king and to the whole assembly.
They decided to send a proclamation throughout Israel, from Beersheba to Dan,2 calling the people to come to Jerusalem and celebrate the Passover to the LORD, the God of Israel. It had not been celebrated in large numbers according to what was written.
References for 2 Chronicles 30:5
At the king's command, couriers went throughout Israel and Judah with letters from the king and from his officials, which read: "People of Israel, return to the LORD, the God of Abraham, Isaac and Israel, that he may return to you who are left, who have escaped from the hand of the kings of Assyria.
Do not be like your fathers3 and brothers, who were unfaithful4 to the LORD, the God of their fathers, so that he made them an object of horror,5 as you see.
References for 2 Chronicles 30:7
Do not be stiff-necked,6 as your fathers were; submit to the LORD. Come to the sanctuary, which he has consecrated forever. Serve the LORD your God, so that his fierce anger7 will turn away from you.
References for 2 Chronicles 30:8
If you return8 to the LORD, then your brothers and your children will be shown compassion9 by their captors and will come back to this land, for the LORD your God is gracious and compassionate.10 He will not turn his face from you if you return to him."
References for 2 Chronicles 30:9
The couriers went from town to town in Ephraim and Manasseh, as far as Zebulun, but the people scorned and ridiculed11 them.
References for 2 Chronicles 30:10
Nevertheless, some men of Asher, Manasseh and Zebulun humbled12 themselves and went to Jerusalem.13
References for 2 Chronicles 30:11
Also in Judah the hand of God was on the people to give them unity14 of mind to carry out what the king and his officials had ordered, following the word of the LORD.
References for 2 Chronicles 30:12
A very large crowd of people assembled in Jerusalem to celebrate the Feast of Unleavened Bread15 in the second month.
References for 2 Chronicles 30:13