"I accept his challenge and invite him to come to visit Lahad Datu and Semporna without being escorted by his crowd of bodyguards and police and army security cordon.
"I will donate the RM501 from Ahmad Zahid to the Tabung Wira Lahad Datu (Lahad Datu Heroes Fund) for the benefit of the families of the fallen heroes who were sacrificed in defending Sabah during the Lahad Datu Tanduo intrusion in March 2013.
"If Ahmad Zahid keeps his promise to pay the RM501 upon being slapped, I am confident that Sabahans will contribute more than 10 times to the Fund," he said in a statement here.
Ahmad Zahid on Tuesday, during the Home Ministry monthly assembly, offered to pay RM501 to a former Sabah Chief Minister if he dared to slap him.
His offer of RM501 was RM1 more than the RM500 offered by Yong to anybody who slaps Ahmad Zahid in his next visit to Sabah.
"I hope Ahmad Zahid will not break his promise like what he had done when he failed to reveal the names of the three opposition leaders whom he alleged were behind the Lahad Datu Tanduo intrusion.
"Last year, on the eve of early polling by security forces and families at the 13th General Election, Zahid had claimed that the three opposition leaders involved in the Lahad Datu Tanduo intrusion will be revealed after the elections.
"But to date, he has failed to do so and kept his silence on the matter," he said.
Yong said the people of Sabah have suffered too long because of the failure of the Federal Government to fulfil its constitutional duty to secure Sabah from foreign intrusions and cross-border violent crimes, resulting in a loss of confidence on the authorities.
"The recent cross-border abductions of tourists have inevitably caused severe damage to the economy as well.
"We can imagine the extreme trauma currently faced by the kidnap victims and the anguish felt by the victims' families.
Perhaps the Ministers do not feel the suffering of the people in Sabah. "Enough is enough!" he said.