I remember reading Witsius before (I think in "The Economy of the Covenants"), where he said the ancient Jews had a saying...about believing in the "three in one." I think he touches on this too in his work on the Apostles Creed, but I'm pretty sure the quote I'm thinking of was in his work on the covenants. Could someone more familiar with Witsius than I give an idea what section of his work I could find this in? And if you have the work available with you, maybe the page number too? Thank you!