He told them another parable: “The kingdom of heaven is like a mustard seed, which a man took and planted in his field. Though it is the smallest of all your seeds, yet when it grows, it is the largest of garden plants and becomes a tree, so that the birds of the air come and perch in its branches.” (Matthew 13:31-32)
And again He said, “To what shall I liken the kingdom of God? It is like leaven, which a woman took and hid in three measures of meal till it was all leavened.” (Luke 13:20-21)