Salesforce CEO Marc Benioff has some strong words for his fellow tech giants, who he says haven’t put enough of their hearts and minds into charitable giving.

He even made a subtle criticism of fellow San Franciscan Mark Zuckerberg, for the latter’s recent billion-dollar donation to the Silicon Valley Community Foundation.

“Silicon Valley Community Foundation is a bunch of DAFs: donor-advised funds. You give your money to SVCF and you get your tax write-off for the year, but [the foundation] has no obligation to administer that money,” said Benioff, in a recent tell-all interview with San Francisco magazine.

When the magazine asked if Benioff thinks Zuckerberg’s donation is just a big tax write-off, Benioff responded:

Where’s it gone? What good is it doing now? I’m sure his intentions are positive, but we need to see that money get distributed. What are his targets? What are his philanthropic interests? We know that he has a political interest with his 501(c)(4) [, a lobbying group pushing for tech-friendly federal policies], but what are his philanthropic interests?

Zuckerberg has a pattern of donating large sums of money to catch-all charities, such as $100-million for Newark’s schools (although that city is still figuring out what to do with all the money).

Benioff himself has become one of San Francisco’s most outspoken mega-philanthropists, endowing hospitals that carry his name and calling out his fellow tech CEOs to do more to help out the city’s beleaguered lower- and middle-class residents. He launched “SF Gives” foundation with the intent of raising millions from major tech companies.

“We have to keep a light on this idea that if you come to San Francisco, you need to also be committed to giving back,” Benioff told the SF Chronicle at his new foundation’s launch. “You can’t just take from our city. You can’t just come here from another city, another state, another country, start a company, take advantage of all of our resources — and then leave with all of your money that you created.”

Benioff contends that a good charity is one that has “tangible outcomes,” such as the opening of a hospital or program to help educate the unemployed. “We want to have clear, tangible examples of our money being put to use.”

Benioff and fellow investor Ron Conway have been especially vocal about giving back to the local community, in light of on-going protests against the housing gentrification partly caused by the flood of wealthier tech employees into the city. According to Benioff, this isn’t the case with everyone.

“You get CEOs who don’t believe that organizations or individuals should give back,” he told San Francisco, going on to describe a conversation with a “famous CEO” who refused to help out because his company is not based in S.F. and whose “factory is not in in S.F.”

There aren’t too many companies that fit Benioff’s description. Apple, Samsung, and Intel would be the most likely culprits — although Benioff didn’t say who the CEO was.

Criticizing philanthropic giving is not a common tactic among the ultra-rich, so Benioff’s words are bound to make waves. We’ll see if they have the intended impact on charitable giving in the city soon enough.