{5} Another parable put he forth unto them, saying, The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field:

(5) God begins his kingdom with very small beginnings so that by its growing (even though men neither hope nor expect it to) his mighty power and working may be displayed all the more.

People's New Testament

13:31 Like to a grain of mustard seed. Compare Lu 13:18-21. The Jews grew mustard in their gardens. Its round seed was previously spoken of as the smallest thing, as it was the smallest seed planted.

Wesley's Notes

13:31 He proposed to them another parable - The former parables relate chiefly to unfruitful hearers; these that follow, to those who bear good fruit. The kingdom of heaven - Both the Gospel dispensation, and the inward kingdom. Mark 4:30; Luke 13:18.

Scofield Reference Notes

[2] Another parable

The parable of the Mustard Seed prefigures the rapid but unsubstantial growth of the mystery form of the kingdom from an insignificant beginning Acts 1:15 2:41 1Cor 1:26 to a great place in the earth. The figure of the fowls finding shelter in the branches is drawn from Dan 4:20-22. How insecure was such a refuge the context in Daniel shows.

Margin kingdom

See Scofield Note: "Mt 3:2".

Jamieson-Fausset-Brown Bible Commentary

31. Another parable put he forth unto them, saying, The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field;

Matthew Henry's Concise Commentary

13:31-35 The scope of the parable of the seed sown, is to show that the beginnings of the gospel would be small, but its latter end would greatly increase; in this way the work of grace in the heart, the kingdom of God within us, would be carried on. In the soul where grace truly is, it will grow really; though perhaps at first not to be discerned, it will at last come to great strength and usefulness. The preaching of the gospel works like leaven in the hearts of those who receive it. The leaven works certainly, so does the word, yet gradually. It works silently, and without being seen, Mr 4:26-29, yet strongly; without noise, for so is the way of the Spirit, but without fail. Thus it was in the world. The apostles, by preaching the gospel, hid a handful of leaven in the great mass of mankind. It was made powerful by the Spirit of the Lord of hosts, who works, and none can hinder. Thus it is in the heart. When the gospel comes into the soul, it works a thorough change; it spreads itself into all the powers and faculties of the soul, and alters the property even of the members of the body, Ro 6:13. From these parables we are taught to expect a gradual progress; therefore let us inquire, Are we growing in grace? and in holy principles and habits?