Looking at the epistle in its entirety, I imagine that Paul is probably referencing back to his first paragraph when he says Timothy needs to charge certain persons not to teach a different doctrine, nor devote oneself to myths or genealogies, which promote speculations, etc. It is difficult to know exactly whom Timothy is referring to. My guess is that there were some Jewish sects involved in angel adoration, or were perhaps concerned with blood relation to Abraham, or Levitical lines, or something of that nature. It could also refer to teachings that are mentioned in passing in Hebrews, where angel worship or devotion is rebuked. Its hard to say here. Since we don’t have the precipitating letter from Timothy to Paul, we can speculate, but can’t determine with certainty.