Many people promise themselves the first thing they’d do if they became millionaires is pay off their parents’ mortgage. But despite having two Oscars and an estimated $150 million fortune, Quentin Tarantino has vowed his mother will never see a penny of it.

And it’s all because when he was 12 years old, his mom once mocked his writing ambitions. Connie Zastoupil was at her wits’ end after teachers told her he wasn’t concentrating on the lesson—and he’s still punishing her decades later.

Speaking on The Moment podcast with host Brian Koppelman, Tarantino previously revealed: “My mom always had a hard time about my scholastic non-ability,” adding that she “was b–ching at me” about writing screenplays. 

“And then in the middle of her little tirade, she said, ‘Oh, and by the way, this little ‘writing career,’ with the finger quotes and everything. This little ‘writing career’ that you’re doing? That s— is over.’”

That last line there prompted the “Once Upon a Time in Hollywood” director to make a promise to himself that he’s still holding onto today—and that vow is currently going viral years later on social media.

“When she said that to me in that sarcastic way, I was in my head and I go, ‘OK lady, when I become a successful writer, you will never see one penny from my success. There will be no house for you. There’s no vacation for you, no Elvis Cadillac for mommy. You get nothing because you said that.’”

And he’s stuck to it, with one exception. Tarantino said he’s still never bought his mother a house or a car, though “I helped her out of a jam with the IRS.”

Tarantino went on to write and direct Reservoir Dogs, Pulp Fiction, Kill Bill, Django Unchained, cementing his status as one of Hollywood’s most successful filmmakers in Hollywood—and has earned millions in the process. His mother, who is a 75-year-old nurse living in Tennessee, hasn’t seen any of it.

Tarantino grew up with a teen mom who let him drop out of school at 15

Koppelman urged Tarantino to forget his vow, because his moms jab might have helped fuel his drive to succeed, as opposed to hindering it, by pushing him to prove her wrong. But he was having none of it: “Remember: There are consequences for your sarcastic tone about what’s meaningful to them,” Tarantino said.

His mother may have mocked his writing, but she also had a hand in making him the filmmaker he is today.

She was just 16 when she gave birth to him in Knoxville, Tennessee, in 1963. His father, an aspiring actor named Tony Tarantino, left before he was born, and she raised her son while working double shifts as a nurse. 

After moving to Los Angeles, she let him watch far more than most kids. Her then-husband, musician Curtis Zastoupil, took him to film screenings, and she allowed him to see grown-up films like Carnal Knowledge and Deliverance.

By 14, he’d written a screenplay called Captain Peachfuzz and the Anchovy Bandit. And by 16, she allowed him to drop out of highschool, as long as he got a job.

He became an usher at a Torrance cinema, then spent five years working at the video store Video Archives, soaking up every film on the shelves—and the rest is history. “When people ask me if I went to film school, I tell them, ‘No, I went to films,’” Tarantino once told Rolling Stones. 

Tarantino’s best money advice: ‘Don’t become an employee of your house’

Tarantino isn’t just stingy with his mother. He’s also living in the same home since 1996—and he didn’t splash out on the LA mansion until long after he could afford it.

And he even warned fellow Hollywood director Eli Roth to be careful not to get trapped by the lifestyle that comes with success.

“‘Don’t buy a house as soon as you’re successful, hold on to your money,’ Tarantino told Roth, advising him to wait “until you can afford to completely pay for it outright.”

Many in the industry use their first million-dollar paycheck to get a mortgage, Roth told Fortune. “But you basically become an employee of your house. So every decision that you make becomes, ‘Can I pay my mortgage?’ Not, ‘Is this best for my career?’

Tarantino told Roth that he waited years before purchasing his current home for exactly that reason: “He goes, ‘I didn’t buy a house until Jackie Brown. Everyone else thought I was going to buy one after Pulp Fiction. I waited because I didn’t want to get stuck being an employee of my house—and then I didn’t have to worry about it.”

Roth took the advice to heart. After Hostel, which cost $3.8 million and made $80 million, “all I could hear was Quentin’s words in my head,” he said. He kept renting and didn’t buy a house until he was 35, in 2007. “If I was stuck as an employee of my house, I would have had to take some directing job that I wouldn’t want to do, and then I would have missed the opportunity of a lifetime.”

It’s a mantra shared by Warren Buffett, who still lives in the Omaha house he bought for $31,500 in 1958.