In a message to employees last week, Ma said that many workers lack the opportunity to put in extra hours at work, so those with the option should take full advantage of it.
"I personally think that being able to work 996 is a huge blessing," Ma said Thursday in remarks posted on Alibaba's WeChat account. The so-called "996" schedule refers to working 9 a.m. to 9 p.m., six days a week.
The e-commerce entrepreneur was weighing in on a growing debate around work-life balance that has emerged among Chinese tech employees in recent weeks.
Last month, activists on Microsoft's code-sharing site GitHub set up a discussion group called "996.ICU," suggesting that employees who work those hours could experience burnout and end up in an intensive care unit.
"Many companies and many people don't have the opportunity to work 996," Ma continued, referring to under-performing firms. "If you don't work 996 when you are young, when can you ever work 996?"
The 54-year-old former teacher, who is today one of China's richest people, noted that he and his fellow co-founders all put in long hours in Alibaba's early days. He said that dedication was vital to the company's success.
"Let me ask everyone, if you don't put out more time and energy than others, how can you achieve the success you want?" Ma wrote. "Compared to them, up to this day, I still feel lucky, I don't regret (working 12 hour days), I would never change this part of me."
Perhaps unsurprisingly, Ma's comments were met with a backlash online, where many commentators argued that overtime hours are a huge blessing for employers only.
"Well, for him it is a blessing. Just not for his employees," one contributor wrote on Reddit.
Ma is not alone in his advocacy for overtime. In November, fellow billionaire entrepreneur and Tesla founder Elon Musk, a fervent advocate of long working hours, tweeted that "nobody ever changed the world on 40 hours a week."
However, the Alibaba chairman tempered his comments on Sunday, saying that the decision to work overtime should be taken by employees, rather than enforced by employers. Companies that try to force such practices are "foolish" and doomed to fail, he said.
"No one likes working at a company that forces you to do '996'. Not only is it inhumane, it's unhealthy and even more unsustainable for long periods plus workers, relatives and the law do not approve of it," he wrote in a post on Chinese micro-blogging site Weibo.
"If you find a job you like, the 996 problem does not exist; if you're not passionate about it, every minute of going to work is a torment," he added.
Ma's comments come after an opinion piece in Chinese state newspaper the People's Daily on Thursday argued on that 996 violate's the country's labor law. The law stipulates that average work hours cannot exceed 40 hours per week.
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