Then Josiah kept the Passover to the LORD in Jerusalem, and the Passover lamb was slaughtered on the fourteenth day of the first month.
The destruction which Josiah made of idols and idolatry was more largely related in the Kings, but just mentioned here in the foregoing chapter (v. 33); but his solemnizing the passover, which was touched upon there (Kg2 23:21), is very particularly related here. Many were the feasts of the Lord, appointed by the ceremonial law, but the passover was the chief.
Commenting on 2 Chronicles 35:1-19
Moreover, Josiah kept a passover unto the Lord in Jerusalem,.... Where only it was to be kept: and they killed the passover on the fourteenth day of the first month; the month Nisan, as the Targum, which was the exact time of killing the passover lamb, according to the law of Moses, Exo 12:6, in the Vulgate Latin version of the Apocrypha in:"And Josias held...
Moreover Josiah kept a passover unto the LORD in Jerusalem: and they killed the passover on the fourteenth [day] of the first month. (a) The scripture in various places calls the lamb the "passover" even though it is only the sign of the passover for in all sacraments the signs have the names of the things signified.