Jn 1:29,36, Isa 53:6-8, Acts 8:31-35, 1 Pt 1:19, Rev 5:6
In the Old Testament, King Josiah of Judah had the Israelites keep the Passover recorded in the covenant book. (2 Kings 23:21-23)
2 Kings 23:21 And the king commanded all the people, saying, Keep the passover unto the Lord your God, as it is written in the book of this covenant. 22 Surely there was not holden such a passover from the days of the judges that judged Israel, nor in all the days of the kings of Israel, nor of the kings of Judah; 23 But in the eighteenth year of king Josiah, wherein this passover was holden to the Lord in Jerusalem.
The Old Testament prophesied that Christ would come as the Lamb of God to suffer and die in our place. (Isa 53:6-8)
Isa 53:6 All we like sheep have gone astray; we have turned every one to his own way; and the Lord hath laid on him the iniquity of us all.
7 He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth.
8 He was taken from prison and from judgment: and who shall declare his generation? for he was cut off out of the land of the living: for the transgression of my people was he stricken.
The Ethiopian eunuch had read about the Passover Lamb in the book of Isaiah, but did not know who this Passover Lamb was referring to. Philip explained the book of Isaiah to this eunuch and explained that this Passover Lamb was Jesus. (Acts 8:31-35)
Acts 8:31 And he said, How can I, except some man should guide me? And he desired Philip that he would come up and sit with him. 32 The place of the scripture which he read was this, He was led as a sheep to the slaughter; and like a lamb dumb before his shearer, so opened he not his mouth: 33 In his humiliation his judgment was taken away: and who shall declare his generation? for his life is taken from the earth. 34 And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other man? 35 Then Philip opened his mouth, and began at the same scripture, and preached unto him Jesus.
Jesus is the Lamb of God who took away our sins. (John 1:29,36, 1 Peter 1:19, Revelation 5:6)
John 1:29 The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world. 36 And looking upon Jesus as he walked, he saith, Behold the Lamb of God!
1 Peter 1:19 But with the precious blood of Christ, as of a lamb without blemish and without spot:
Revelation 5:6 nd I beheld, and, lo, in the midst of the throne and of the four beasts, and in the midst of the elders, stood a Lamb as it had been slain, having seven horns and seven eyes, which are the seven Spirits of God sent forth into all the earth.