There were ‘things’ which Paul taught Timothy which he wanted this young man to ‘hold fast’ and to ‘continue…in’. These ‘things’, which Timothy had heard preached and taught by Paul, are described as ‘sound words’ in 2 Timothy 1:13.
By ‘sound words’ are meant doctrines, namely, the great doctrinal truths which make up the Gospel of Jesus Christ. This is not referring to mere words, for the servants of the Lord are warned against striving about words, to no profit: Of these things put them in remembrance, charging them before the Lord that they strive not about words to no profit, but to the subverting of the hearers,” 2 Timothy 2:14. The Greek word translated ‘words’ in 2 Timothy 1:13, is translated as ‘doctrine’ in Hebrews 6:1: Therefore leaving the principles of the doctrine of Christ, let us go on unto perfection; not laying again the foundation of repentance from dead works, and of faith toward God.