1 Corinthians 11:28

He is to examine himself about his knowledge, whether he rightly understands what Christ is, what the nature of the sacrament is, what he doth in that sacred action; about his faith, love, repentance, new obedience, whether he be such a one as God hath prepared that holy table for; it is the children's bread, and not for dogs; a table Christ hath spread for his friends, not for his enemies. And so let him eat, &c.; having so examined himself, not otherwise. Whence it appears, that neither children in age or understanding, nor persons not in the use of their reason, nor unbelievers, nor persons under the guilt of sins not repented of, have any right to the Lord's supper: accordingly was the practice of all the primitive churches, and all rightly reformed churches. Whether they ought, if they will presume to come, to be kept away by the officers of the church, and how, and by whom? Whether good Christians may communicate with such at the holy table? And after what previous duty performed? Are questions that belong not to this text.