The “it” is The Passover
The cup refers to the Passover
let this cup pass from me
The passover sacrifice prefigured the sacrifice of Christ
Christ was celebrating the Passover and changing it into the new covenant Passover in his own body and blood
Began in the last supper with the psalm then to the garden and ended with his death in the cross with the words commanded to be said at the consummation of the Passover sacrifice by the high priest “IT IS FINISHED”!!!
jn 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.
1 cor 10:16 The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ?
1 cor 11:23 For I have received of the Lord that which also I delivered unto you, that the Lord Jesus the same night in which he was betrayed took bread:
24 And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: this do in remembrance of me.
25 After the same manner also he took the cup, when he had supped, saying, this cup is the new testament in my blood: this do ye, as oft as ye drink it, in remembrance of me.
26 For as often as ye eat this bread, and drink this cup, ye do shew the Lord's death till he come.
Notice the connection to his betrayal and death
1 cor 5:6-8
For even Christ our passover is sacrificed for us: Therefore let us keep the feast
but something is missing we have to eat the lamb
jn 6:53 Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you.
54 Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day.
55 For my flesh is meat indeed, and my blood is drink indeed.
56 He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him.
57 As the living Father hath sent me, and I live by the Father: so he that eateth me, even he shall live by me.