Proof?
Here's what he said
"But to be plain, you are dissatisfied with me about the negro. Quite likely there is a difference of opinion between you and myself upon that subject. I certainly wish that all men could be free, while I suppose that you do not.
Yet I have neither adopted nor proposed any measure, which is not consistant even with your view, provided you are for the Union.
I suggested compensated emancipation; to which you replied you wished not to be taxed to buy negroes. But I had not asked you to be taxed to buy negroes, except in such way, as to save you from greater expense, to save the Union exclusively by other means. You dislike the emancipation proclamation; and perhaps, would have it retracted. You say it is unconstitutional--I think differently. I think the Constitution invests the commander in chief with the law of war, in time of war. The most that can be said, if so much, is, that slaves are property. Is there--has there ever been--any question that by the law of war, property, both of enemies and friends, may be taken when needed? And is it not needed whenever taking it helps us, or hurts the enemy?
....but the proclamation, as law, either is valid, or it is not valid. If it is not valid, it needs no retraction. If it is valid, it can not be retracted, any more than the dead can be brought to life....The war has certainly progressed as favorably for us, since the issue of the proclamation as before. I know as fully as one can know the opinions of others that some of the commanders of our armies in the field who have given us some of most important successes, believe the emancipation policy and the use of colored troops, constitute the heaviest blow yet dealt the rebellion, and that at least one of those important successes could not have been achieved when it was but for the aid of black soldiers....I submit these opinions as being entitled to some weight against the objections, often urged, that emancipation, and arming the blacks, are unwise as military measures, and were not adopted, as such, in good faith. You say you will not fight to free negroes. Some of them seem willing to fight for you; but no matter. Fight you then, exclusively to save the Union...
Negroes, like other people act upon motives. Why should they do anything for us if we will do nothing for them? If they stake their lives for us, they must be prompted by the strongest motive--even the promise of freedom. And the promise, being made, must be kept....peace does not appear as distant as it did. I hope it will come soon, and come to stay; and so come as to worth the keeping in all future time. It will have then been proved that, among free men, there can be no successful appeal from the ballot to the bullet; and that they who take such appeal are sure to lose their case, and pay the cost. And then, there will be some black men, who can remember that, with silent tongue, and clenched teeth, and steady eye, and well-poised bayonet they have helped mankind on to this great consumation; while, I fear, there will be some white ones, unable to forget that, with malignant heart, and deceitful speech, have strove to hinder it. Still let us not be over-sanguine of a speedy final triumph. Let us be quite sober. Let us dilligently apply the means, never doubting that a just God, in his own good time, will give us the rightful result."
8/24/63
Should I call you a liar now, or later?
Walt
I did understand however, that my oath to preserve the constitution to the best of my ability, imposed upon me the duty of preserving, by every indispensable means, that government --- that nation --- of which that constitution was the organic law. Was it possible to lose the nation, and yet preserve the constitution? By general law life and limb must be protected; yet often a limb must be amputated to save a life; but a life is never wisely given to save a limb. I felt that measures, otherwise unconstitutional, might become lawful, by becoming indispensable to the preservation of the constitution, through the preservation of the nation. Right or wrong, I assumed this ground, and now avow it. I could not feel that, to the best of my ability, I had even tried to preserve the constitution, if, to save slavery, or any minor matter, I should permit the wreck of government, country, and Constitution all together. When, early in the war, Gen. Fremont attempted military emancipation, I forbade it, because I did not then think it an indispensable necessity. When a little later, Gen. Cameron, then Secretary of War, suggested the arming of the blacks, I objected, because I did not yet think it an indispensable necessity. When, still later, Gen. Hunter attempted military emancipation, I again forbade it, because I did not yet think the indispensable necessity had come. When, in March, and May, and July 1862 I made earnest, and successive appeals to the border states to favor compensated emancipation, I believed the indispensable necessity for military emancipation, and arming the blacks would come, unless averted by that measure. They declined the proposition; and I was, in my best judgment, driven to the alternative of either surrendering the Union, and with it, the Constitution, or of laying strong hand upon the colored element. I chose the latter.
Abraham Lincoln, "To Albert G. Hodges", 4 Apr 1864, Collected Works Of Abraham Lincoln, (Roy P. Basler, Ed.), Vol VII, p. 281.
I think you'll have to wait.