Numbers 33:3-5

Amplified Bible

³ They set out from Rameses on the fifteenth day of the first month; on the day after the Passover the Israelites moved out triumphantly in the sight of all the Egyptians, ⁴ while the Egyptians were burying all their firstborn whom the Lord had struck down among them. Upon their gods the Lord also executed judgments.

⁵ Then the Israelites moved out from Rameses [where they had all joined together], and camped in Succoth.