The Hebrew "day" begins at sundown and ends at sundown based on Scripture: וַיְהִי-עֶרֶב וַיְהִי-בֹקֶר, יוֹם אֶחָד. And there was evening and there was morning, one day. --Beresheis (Genesis) 1:5
Evening occurs first.
Thus Pesach (Passover) begins at sundown on the night of the fifteenth day of the Hebrew month of Nissan.
Faith and I are into a bit of a discussion, and part of the discussion revolves around whether Passover is observed the evening that would begin the First Day of Unleavened Bread, or the evening... more
Leviticus 23: 4 “‘These are the LORD’s appointed festivals, the sacred assemblies you are to proclaim at their appointed times: 5 The LORD’s Passover begins at twilight on the fourteenth day of the... more
Per Shemot (Exodus) 12: An unblemished lamb or goat is to be set apart on Nisan 10 and slaughtered on Nisan 14 and then to be roasted and eaten "that night" Nisan 15 with unleavened bread and bitter... more