Matthew 13:31-33 NRSV
He put before them another parable: “The kingdom of heaven is like a mustard seed that someone took and sowed in his field; it is the smallest of all the seeds, but when it has grown it is the greatest of shrubs and becomes a tree, so that the birds of the air come and make nests in its branches.”
He told them another parable: “The kingdom of heaven is like yeast that a woman took and mixed in with three measures of flour until all of it was leavened.”
NRSV: New Revised Standard Version