Receiving funds from a questionable source

Is it permissible to receive a monetary donation from a Jew who earned the money by gambling?

Answer: It is permissible to receive such a donation, because although gambling
transgresses the Rabbinic prohibition against obtaining money dishonestly, if it was already done, one can rely on the opinions that the gambler is not obligated to return the money to the place where he ‘earned’ it (the place where he gambled).