I should say, the wording that Jesus is a new covenant to replace the old covenant is not explicitly stated as far as I'm aware. However, there are times in which Mosaic Law is spoken of and Jesus is said to fulfill and perfect it. I can't think of specific examples offhand, but these links may help a bit. The site is a conservative-leaning (IMO) Catholic site. I haven't read the articles myself, but as with anything regarding religion it is important to keep in mind that with pretty much anything you read, with the exception of the most basic teachings such as Jesus being fully mortal yet fully divine, there may be a group of Christians and/or theologians who hold a variant belief. Hopefully these pages can help in finding what you're looking for though...
http://www.newadvent.org/cathen/10582c.htm
http://www.newadvent.org/cathen/09071a.htm
A Biblical exerpt for you as well.... (note: of course, the Bible is a largely interpretive book, so take from this what you will)...
http://www.biblegateway.com/cgi-bin/...atthew+5:13-48
This specific topic and viewpoint is not something I give much consideration to, so bear in mind that I'm basically just throwing stuff out here. I don't know how right or wrong any of this is, but here ya go - hope it helps
