The off-spinner took to his Twitter account to hail the humanitarian effort of the Polish athlete, who claimed silver at the Rio Olympics 2016.
"Humanity🙏🙏 with this lil boy's blessing you gonna win many more medals..but this is ur best medal #savinglife," Singh tweeted.
Earlier on Thursday, the 33-year-old world champion wrote on his Facebook page that he was moved to auction his prize after receiving a letter from the mother of a boy called Olek who said he had been battling eye cancer for 2 years and that treatment in New York was his only hope.
"I fought for gold in Rio. Today I'm calling on everyone to fight for something even more precious," Malachowski wrote on Friday (August 26) to announce the auction.
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"If you help me, my silver medal may turn out to be more precious than gold for Olek," he said, adding that he would use the entire sum raised to pay for treatment.
"Success," he later wrote, saying the medal had found takers.
(With inputs from agencies)