Matthew 13:31-35

He gave another parable, saying, “The kingdom of heaven is like to a grain of mustard seed which a man sowed in his field. It is the smallest of the seeds planted, but when it is grown, it is the biggest of all the herbs. It becomes a tree big enough that the birds come and nest in its branches.”

He gave them another parable, saying to them, “The kingdom of heaven is like yeast, which a woman took and hid in three measures of meal. Soon, the whole thing was leavened.”

Mark 4:30-34

And he said, “To what can we compare the kingdom of God, or what parable can we use to describe it? It is like a grain of mustard seed. And when sown in the ground it is the smallest of the seeds planted. But when it grows, it becomes the largest of all the herbs, with great branches where the birds can perch in its shade.

He told them many such parables, giving them the word to the degree they were able to hear it. But without a parable, he didn’t teach. But when they were alone, he explained everything to his disciples.