Find the cutoff correlation value for Pearson correlation test

Hi,

    I find a few Pearson correlation test functions like

    fBasics::correlationTest or stats::cor.test

which give the p-value of the test result. Is there a function that
calculate the cutoff correlation value for a specific p-value , e.g., p =
0.05?

I have a plot for the cross correlations between two time series, and I
would like to add a horizontal line that marks the significance of the
correlations.