"Continue thou in the things which thou hast learned and hast been assured of, knowing of whom thou hast learned them; and that from a child thou hast known the Holy Scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus" - 2 Tim. 3:14,15
Timothy had been instructed carefully by his godly Jewish mother and grandmother (1:5). So when he heard the gospel he was ready to receive it in all simplicity. Paul exhorts him to continue in the study of and obedience to the sacred writings of the Old testament, which had been the means of preparing his heart for the gospel message.
It is a great thing to learn the Word of God in the family circle. Timothy's mother had given heed to the commandments regarding this, as in Deut. 6. Teaching a child the truth of Scripture is like placing kindling and fuel in order. Then when the match is struck, it bursts into a flame. So Timothy's heart and mind had ben stored with the Word. Paul's preaching brought definite conviction and decision, and so Timothy was made "wise unto salvation through faith which is in Christ Jesus". - H. A. Ironside