Timothy Snyder in his "Black Earth: The Holocaust as history and warning" repeats that claim too.
But it's a fake story which nicely demonstrates Western historians' limited knowledge of Polish history.
Below is the only source of the story:
September 20, 1938
The Chancellor received me today in Obersalzberg in the presence of the Reich minister of foreign affairs, Ribbentrop, at 4 P.M. The conversation lasted for more than two hours. [...]
Chancellor Hitler opened the conversation with me with a statement that events had taken a different turn than he first expected. He then gave a historical outline of the Sudetenland problem, starting from his speech at the Reichstag this February.
Further in the conversation the Chancellor very strongly stressed that Poland is an outstanding factor safeguarding Europe against Russia.
From other long deliberations of the Chancellor the following results were clear:
a ) that he does not intend to go beyond the Sudetenland territory; naturally with armed force he would go deeper, especially since, in my opinion, he would then be under pressure from the military elements who for strategic reasons push toward the subjugation of the whole of ethnographic Czechoslovakia to Germany;
b) that besides a certain line of German interests we have a totally free hand;
c) that he sees great difficulties in reaching a Rumanian-Hungarian agreement (I think the Chancellor is under Horthy's influence, as I reported to you verbally) ;
d) that the cost of the Sudetenland operation, including fortifications and armaments, adds up to the sum of 18 billion RM;
e ) that upon settlement of the Sudetenland question he would present the problem of colonies;
f ) that he has in mind an idea for settling the Jewish problem by way of emigration to the colonies in accordance with an understanding with
Poland, Hungary, and possibly also Rumania (at which point I told him that if he finds such a solution we will erect him a beautiful monument
Following your instructions, I also brought up Polish-German relations in the above conversation, I must mention that the moment was not especially well chosen, since the Chancellor was very much absorbed by his approaching talk with Chamberlain. I referred to the Danzig question, suggesting the possibility of a simple Polish-German agreement to stabilize the situation in the Free City.
from: Diplomat In Berlin 1933 - 1939 by Józef Lipski
The underlined sentence wasn't part of the typewritten report it was added later in pencil by Lipski, he didn't discuss or assure anything he merely stated jokingly that the Jewish problem in Poland was unsolvable.
As a rule, Polish diplomats didn't respond to new, unexpected proposals especially "long vague deliberations." It was considered unprofessional and harmful.
"to invite the Poles to participate in the attack on Czechoslovakia and share in the spoils" is nonsense too but it comes from an especially ignorant "historian." Any cooperation with the Germans was avoided for internal political reasons.
The Poles didn't discuss the problem with Hitler but it's true they discussed it many times with Britain, France, and the US, mostly focusing on finding new territories for the Jews or even receiving a mandate for Palestine.
It was done for prestige reasons and because many influential but deluded people in Poland believed Poland needed colonies.