Leviticus 23:17 Ye shall bring out of your habitations two wave loaves of two tenth deals: they shall be of fine flour; they shall be baken with leaven; they are the firstfruits unto the LORD.

Matthew 13:33 ¶Another parable spake he unto them; The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till the whole was leavened.

1 Corinthians 5:7 Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us:

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.

Amos 4:5 And offer a sacrifice of thanksgiving with leaven, and proclaim and publish the free offerings: for this liketh you, O ye children of Israel, saith the Lord GOD.