First Book of Kings (Author Compiled by Isaias from records of Samuel, David, Nathan, and Gad.)
21:2et ait David ad Ahimelech sacerdotem rex praecepit mihi sermonem et dixit nemo sciat rem propter quam a me missus es et cuiusmodi tibi praecepta dederim nam et pueris condixi in illum et illum locum
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.