First Book of Paralipomenon (Author Compiled by Isaias and Esdras from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
21:5deditque David numerum eorum quos circumierat et inventus est omnis Israhel numerus mille milia et centum milia virorum educentium gladium de Iuda autem trecenta septuaginta milia bellatorum
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.