The pastoral letters, like 1 and 2 Timothy MAY have been dictated by Paul but most agree that lots were added to it by others, the downplaying of womens roles for example, soemthing very UNLIKE Paul since he praises/points out women in Romans.
The only scriptures in Paul's time where the Hebrew ones and though it is quite possible that the sayings of Jesus were already in circulation in some form or another, the Gospel was most likely being spread via oral tradition at the time.
But what does Paul say? He says:
10 Now you have observed my teaching, my conduct, my aim in life, my faith, my patience, my love, my steadfastness, 11 my persecutions, and my suffering the things that happened to me in Antioch, Iconium, and Lystra. What persecutions I endured! Yet the Lord rescued me from all of them. 12 Indeed, all who want to live a godly life in Christ Jesus will be persecuted. 13 But wicked people and impostors will go from bad to worse, deceiving others and being deceived. 14 But as for you, continue in what you have learned and firmly believed, knowing from whom you learned it, 15 and how from childhood you have known the sacred writings that are able to instruct you for salvation through faith in Christ Jesus. 16 All scripture is inspired by God and is b useful for teaching, for reproof, for correction, and for training in righteousness, 17 so that everyone who belongs to God may be proficient, equipped for every good work.
Remember that Timothywas Part Jew, so obviously the scripture he was exposed to since childhood was the Hebrew scriptures.
Note that Paul says WHAT the scriptures are good for:
Teaching, reproof, correction and training of doing whatis right.
Paul doesn't go beyond that, nor does Paul place scripture as the WORD of God but simply inspired BY God ( the writers were inspired by God to write down what was written).
