Then death and Hades were thrown into the lake of fire. The lake of fire is the second death.
Matthew 15:10-11, 17-18
And He called the people to Him and said to them, “Hear and understand: it is not what goes into the mouth that defiles a person, but what comes out of the mouth; this defiles a person.” Do you not see that whatever goes into the mouth passes into the stomach and is expelled? But what comes out of the mouth proceeds from the heart, and this defiles a person.
…only what is within you.