Deuteronomy 11:18-21 (NIV) 18 Fix these words of mine in your hearts and minds; tie them as symbols on your hands and bind them on your foreheads. 19 Teach them to your children, talking about them when you sit at home and when you walk along the road, when you lie down and when you get up. 20 Write them on the doorframes of your houses and on your gates, 21 so that your days and the days of your children may be many in the land that the LORD swore to give your forefathers, as many as the days that the heavens are above the earth.
2 Chronicles 17:9 (NIV) 9 They taught throughout Judah, taking with them the Book of the Law of the LORD; they went around to all the towns of Judah and taught the people.
1 Corinthians 15:1-2 (NIV) 1 Now, brothers, I want to remind you of the gospel I preached to you, which you received and on which you have taken your stand. 2 By this gospel you are saved, if you hold firmly to the word I preached to you. Otherwise, you have believed in vain.
"The gospel preached by Paul in the early years was the gospel still being preached by him years later."—James Montgomery Boice (From Generation to Generation)