2CH 30:1

1 The king and his officials and all the other people who had gathered in Jerusalem wanted to celebrate the Passover Festival. But they were not able to celebrate it at the usual time, because many of the priests had still not performed the rituals to purify themselves; therefore they were not allowed to do serve in the festival. Also, everyone had still not come to Jerusalem [to celebrate the Passover]. So they decided to celebrate it one month later than usual.