Matthew 13:44-45

The kingdom of heaven is like unto a treasure hidden in a field. Which a man having found, hid it, and for joy thereof goeth, and selleth all that he hath, and buyeth that field. Again the kingdom of heaven is like to a merchant seeking good pearls. Who when he had found one pearl of great price, went his way, and sold all that he had, and bought it.

Commentary
By St. John Chryostom

Much as in the other place, the mustard seed and the leaven have but some little difference from each other, so here also these two parables, that of the treasure and that of the pearl. This being of course signified by both, that we ought to value the gospel above all things. And the former indeed, of the leaven and of the mustard seed, was spoken with a view to the power of the gospel, and to its surely prevailing over the world; but these declare its value, and great price. For as it extends itself like mustard seed, and prevails like leaven, so it is precious like a pearl, and affords full abundance like a treasure. We are then to learn not this only, that we ought to strip ourselves of everything else, and cling to the gospel, but also that we are to do so with joy; and when a man is dispossessing himself of his goods, he is to know that the transaction is gain, and not loss.

Seest thou how both the gospel is hid in the world, and the good things in the gospel?

Except thou sell all, thou buyest not; except thou have such a soul, anxious and inquiring, thou findest not. Two things therefore are requisite, abstinence from worldly matters, and watchfulness. For He saith "One seeking goodly pearls, who when he had found one of great price, sold all and bought it." For the truth is one, and not in many divisions.

And much as he that hath the pearl knows indeed himself that he is rich, but others know not, many times, that he is holding it in his hand (for there is no corporeal bulk); just so also with the gospel, they that have hold of it know that they are rich, but the unbelievers, not knowing of this treasure, are in ignorance also of our wealth.