Wiktionary
keep to
vb. To adhere strictly to; not to neglect or deviate from.
Usage examples of "keep to".
He guessed, however, that the valley would not take him far out of his way, and decided to keep to that for the time being, much as he hated and feared it.
If you can get it for me, I will pay you what it is worth and make it back by selling what I do not keep to taste for myself.
That is to say, I imagine that any piece of information you gave me I should prefer to keep to myself and my colleagues.