Another stock ACW soundbite traced to its' source, in this case much more reputable. Alexander McClure reports them in 1892, in response to his attempt to have Grant removed (although Lincoln never did intervene, and it was Halleck that reinstated Grant to avoid McClernand getting an army). Brooks Simpson has shown it also to be false.
Also of interest is Lincoln's response to the suggested gerrymandering of the 1864 election in Pennsylvania (ref),Lincoln is concerned that unlike Sherman, Grant might not actually selectively furlough Republican voters. Lincoln thinks Grant is incorruptible; I regard this as high praise for Grant.