Matthew 13:46

46.And bought it. By the word buy Christ does not mean, that men bring any price, with which they may purchase for themselves the heavenly life; for we know on what condition the Lord invites believers in the book of Isaiah, (Isaiah 55:1,) Come and buy wine and milk without money and without price. But though the heavenly life, and every thing that belongs to it, is the free gift of God, yet we are said to buy it, when we cheerfully relinquish the desires of the flesh, that nothing may prevent us from obtaining it; as Paul says, that he

reckoned all things to be loss and dung, that he might gain Christ,
(Philippians 3:8.)