Highly unlikely Grant ever said this. For one thing, its grandiloquence was not in his character.
Whatever else you may say about the man, he wasn't flashy.
I have a book entitled “The Politically Incorrect Guide to American History” by Thomas E. Woods Jr., Ph.D. I copied that quote from that book. If you know anything negative about the author or the book please let me know as I use the information in it.
Side note: On a TV show this AM it depicted Grant as a drunk, and quoted Lincoln as asking what he drank so he could give it to the rest of the Union army, because Grant was winning.