Matthew 13:33

Then He told them another parable: "The kingdom of heaven is similar to yeast, which a woman worked into a batch of dough [i.e., the amount was over half a bushel], until [the dough] was completely leavened [by it]."

Romans 8:23

And not just the world, but even we [Christians] ourselves, who have the firstfruits of the Holy Spirit [i.e., the first installment of our inheritance from God] also groan within us, eagerly waiting to be adopted as [God's] children, and receive back our bodies [i.e., in the resurrection].

1 Corinthians 15:20

But now Christ has been raised up from the dead; [He is] the firstfruits of those who have died. [Note: By "firstfruits" is meant the first installment of the crop which promises the entire harvest eventually].

James 1:18

It was God's purpose to bring us into being [spiritually] by the message of truth, so that we could become a kind of "firstfruits" of those He created. [Note: "Firstfruits" here suggests either that Christians are the best of all of God's creatures (Num. 18:12), or that they were the first to be converted, with many more to come].

Revelation 14:4

These people are the ones who did not practice sexual immorality with women, for they were virgins [Note: This probably has reference to people who avoided idolatry]. These are people who followed the Lamb wherever He went. They were purchased from among mankind to be the firstfruits [devoted] to God and to the Lamb.

Treasury of Scripture Knowledge

Summary

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.

Leaven

Bible References

Leaven

Matthew 13:33
Then He told them another parable: "The kingdom of heaven is similar to yeast, which a woman worked into a batch of dough [i.e., the amount was over half a bushel], until [the dough] was completely leavened [by it]."