How are they that receive the sacrament of the Lord's supper to prepare themselves before they come unto it?

They that receive the sacrament of the Lord’s supper are, before they come, to prepare themselves thereunto, by examining themselves [1] of their being in Christ,[2] of their sins and wants;[3] of the truth and measure of their knowledge,[4] faith,[5] repentance;[6] love to God and the brethren,[7] charity to all men,[8] forgiving those that have done them wrong;[9] of their desires after Christ,[10] and of their new obedience;[11] and by renewing the exercise of these graces,[12] by serious meditation,[13] and fervent prayer.[14]

1. I Cor. 11:28

   Let a person examine himself, then, and so eat of the bread and drink of the cup.

2. II Cor. 13:5

   Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you?—unless indeed you fail to meet the test!

3. I Cor. 5:7

   Cleanse out the old leaven that you may be a new lump, as you really are unleavened. For Christ, our Passover lamb, has been sacrificed.

   Exod. 12:15

   Seven days you shall eat unleavened bread. On the first day you shall remove leaven out of your houses, for if anyone eats what is leavened, from the first day until the seventh day, that person shall be cut off from Israel.

4. I Cor. 11:29

   For anyone who eats and drinks without discerning the body eats and drinks judgment on himself.

5. I Cor. 13:5

   …or rude. It does not insist on its own way; it is not irritable or resentful….

   Matt. 26:28

   …for this is my blood of the covenant, which is poured out for many for the forgiveness of sins.

6. Zech. 12:10

   And I will pour out on the house of David and the inhabitants of Jerusalem a spirit of grace and pleas for mercy, so that, when they look on me, on him whom they have pierced, they shall mourn for him, as one mourns for an only child, and weep bitterly over him, as one weeps over a firstborn,

   I Cor. 11:31

   But if we judged ourselves truly, we would not be judged.

7. I Cor. 10:16-17

   The cup of blessing that we bless, is it not a participation in the blood of Christ? The bread that we break, is it not a participation in the body of Christ? Because there is one bread, we who are many are one body, for we all partake of the one bread.

   Acts 2:46-47

   And day by day, attending the temple together and breaking bread in their homes, they received their food with glad and generous hearts, praising God and having favor with all the people. And the Lord added to their number day by day those who were being saved.

8. I Cor. 5:8

   Let us therefore celebrate the festival, not with the old leaven, the leaven of malice and evil, but with the unleavened bread of sincerity and truth.

   I Cor. 11:18, 20

   For, in the first place, when you come together as a church, I hear that there are divisions among you. And I believe it in part…
   
   When you come together, it is not the Lord’s supper that you eat. 

9. Matt. 5:23-24

   So if you are offering your gift at the altar and there remember that your brother has something against you, 24leave your gift there before the altar and go. First be reconciled to your brother, and then come and offer your gift.

10. Isa. 55:1

    Come, everyone who thirsts,
    come to the waters;
    and he who has no money,
    come, buy and eat!
    Come, buy wine and milk
    without money and without price.

    John 7:37

    On the last day of the feast, the great day, Jesus stood up and cried out, “If anyone thirsts, let him come to me and drink.

11. I Cor. 5:7-8

    Cleanse out the old leaven that you may be a new lump, as you really are unleavened. For Christ, our Passover lamb, has been sacrificed. 8Let us therefore celebrate the festival, not with the old leaven, the leaven of malice and evil, but with the unleavened bread of sincerity and truth.

12. I Cor. 11:25-26, 28

     In the same way also he took the cup, after supper, saying, “This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me.”  For as often as you eat this bread and drink the cup, you proclaim the Lord’s death until he comes.

    Let a person examine himself, then, and so eat of the bread and drink of the cup.

    Heb. 10:21-22, 24

    …and since we have a great priest over the house of God, 22let us draw near with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water.

     And let us consider how to stir up one another to love and good works…

    Psa. 26:6

    I wash my hands in innocence
    and go around your altar, O Lord…

13. I Cor. 11:24-25

    …and when he had given thanks, he broke it, and said, “This is my body which is for you. Do this in remembrance of me.” In the same way also he took the cup, after supper, saying, “This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me.”

14. II Chr. 30:18-19

    For a majority of the people, many of them from Ephraim, Manasseh, Issachar, and Zebulun, had not cleansed themselves, yet they ate the Passover otherwise than as prescribed. For Hezekiah had prayed for them, saying, “May the good Lord pardon everyone 19who sets his heart to seek God, the Lord, the God of his fathers, even though not according to the sanctuary’s rules of cleanness.”

    Matt. 26:26

    Now as they were eating, Jesus took bread, and after blessing it broke it and gave it to the disciples, and said, “Take, eat; this is my body.”

Question 171, Westminster Larger Catechism