Combine butter and sugar; beat well. Add eggs, flour, and vanilla; mix well. Stir in pecans.
Divide dough into three equal portions; shape each portion into a 12- x 2-inch roll. Wrap in waxed paper, and refrigerate overnight.
Slice dough into 1/4-inch-thick slices; place slices on ungreased baking sheets. Bake at 350° for 10 minutes or until lightly browned. Remove to wire racks to cool.