2:3 so great salvation. Salvation is indeed a great truth! The very name “Jesus” means “salvation.” It embraces many major doctrines of Scripture—including such doctrines as atonement (Leviticus 17:11), substitution (Isaiah 53:5), imputation (Romans 4:6-8), propitiation (I John 2:2), redemption (I Peter 1:18), remission (Acts 10:43), justification (Romans 3:28), adoption (Ephesians 1:5), reconciliation (Romans 5:10-11), regeneration (Titus 3:5), sanctification (Hebrews 10:9-10, and glorification (Romans 8:30).
2:3 that heard him. The words of the gospel of salvation were first spoken by Christ, then confirmed in writing by His apostles. Also, note Hebrews 1:2.