Keach's Catechism · 1794

Q108. What is required to the worthy receiving of the Lord's Supper?

It is required of them that would worthily (that is, suitably) partake of the Lord's Supper, that they examine themselves, of their knowledge to discern the Lord's body; of their faith to feed upon Him; of their repentance, love, and new obedience: lest, coming unworthily, they eat and drink judgment to themselves.
Answer · Keach's Catechism

Scripture proofs

  1. [1]
    1 Corinthians 11:27-31

    Wherefore whosoever shall eat this bread, and drink this cup of the Lord, unworthily, shall be guilty of the body and blood of the Lord. But let a man examine himself, and so let him eat of that bread, and drink of that cup. For he that eateth and drinketh unworthily, eateth and drinketh damnation to himself, not discerning the Lord’s body. …

    1 Corinthians 5:8

    Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth.

    2 Corinthians 13:5

    Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?

Proof texts as given in the original; verse text from the King James Version.