Exodus 12:15
14 “‘This day will become a memorial for you, and you will celebrate it as a festival to the Lord—you will celebrate it perpetually as a lasting ordinance. 15 For seven days you must eat bread made without yeast. Surely on the first day you must put away yeast from your houses because anyone who eats bread made with yeast from the first day to the seventh day will be cut off from Israel. 16 “‘On the first day there will be a holy convocation, and on the seventh day there will be a holy convocation for you. You must do no work of any kind on them, only what every person will eat—that alone may be prepared for you. 17 So you will keep the Feast of Unleavened Bread, because on this very day I brought your regiments out from the land of Egypt, and so you must keep this day perpetually as a lasting ordinance.
1 Corinthians 5:5
3 For even though I am absent physically, I am present in spirit. And I have already judged the one who did this, just as though I were present. 4 When you gather together in the name of our Lord Jesus, and I am with you in spirit, along with the power of our Lord Jesus, 5 hand this man over to Satan for the destruction of the flesh, so that his spirit may be saved in the day of the Lord. 6 Your boasting is not good. Don’t you know that a little yeast affects the whole batch of dough? 7 Clean out the old yeast so that you may be a new batch of dough—you are, in fact, without yeast. For Christ, our Passover lamb, has been sacrificed. 8 So then, let us celebrate the festival, not with the old yeast, the yeast of vice and evil, but with the bread without yeast, the bread of sincerity and truth.
Notes and References
"... In chapter 5, Paul condemns the sexual misconduct plaguing the church in Corinth (here, specifically, a case of incest) with a brief mystagogical allusion to Passover and to the cleansing of leaven, which is equated with sin (5:6–8).15 Just as the Jews must cleanse their homes of all leaven before celebrating the feast of Passover, so the Corinthian Christian community must cleanse itself of sin in order to celebrate the festival of Christ, the Paschal Lamb—perhaps an allusion to the Eucharistic celebration of the Corinthian community. The severity of the punishment prescribed in the book of Exodus for eating leavened bread during the feast — being cut off from Israel (see Exodus 12:15, 19) — helps explain the harsh penalty of excommunication that Paul imposes upon the culprit (asking the community to “deliver him to Satan for the destruction of the flesh,” 5:5) ..."
Villeneuve, André Anthropic Temple and Nuptial Symbolism in First Corinthians (pp. 155-171) Letter & Spirit, Vol. 10: Christ Our Passover: Theological Exegesis of St. Paul, 2015