“Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood.” Acts 20:28
The apostle Paul here is advising them to take heed, i.e., to lead by example.
Purchased means we’ve been bought with a price – we’re not our own.
Through that price it means we’re now his purchased possession, purchased by his own blood. He who cannot die, died! He who knew no sin became sin for us; he became the accused for you and I. God used the strategy of Satan for his own glory. The same way David took Goliath’s own sword to cut off his head.
Ephesians 1:13-14 says, “In whom ye also trusted , after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,  Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory.“
He redeemed us to God by his own blood. The eternal God prepared the body of his own son for our redemption. Take heed therefore unto yourselves, and to all the flock, knowing he hath purchased you with his own blood for his own glory, not yours.