That's a gross distortion worthy of the modern media. There is one quote where before the south began hostilities Lincoln said if he could save the union by abolishing slavery he would do so, and if he could save the union by keeping it he would do that. That's like media saying Trump's statement that if Putin had Hillary's missing emails he should release them proves "collusion". There was no deal, Lincoln was making the point that saving the union was his top priority.
There is more than one quote where he said he would keep slavery. In his first inaugural address, he said:
I have no purpose, directly or indirectly, to interfere with the institution of slavery in the States where it exists. I believe I have no lawful right to do so, and I have no inclination to do so.
He also said:
I understand a proposed amendment to the Constitution—which amendment, however, I have not seen—has passed Congress, to the effect that the Federal Government shall never interfere with the domestic institutions of the States, including that of persons held to service. To avoid misconstruction of what I have said, I depart from my purpose not to speak of particular amendments so far as to say that, holding such a provision to now be implied constitutional law, I have no objection to its being made express and irrevocable.
So is it a gross distortion to say that Lincoln was going to make a deal to keep slavery permanently?
I don't think so. It seems pretty clear from his own words when he gave his first speech as President.