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Excerpts of the book "Gambler: Secrets from a Life of Risk" were first reported Thursday by Fire Pit Collective and provide the most detailed look yet at Mickelson's sports gambling and his relationship with Walters, a Las Vegas businessman who is widely considered to be the most successful American bettor ever.

Citing betting records and "two very reliable sources," Walters writes that from 2010 to 2014, Mickelson made 858 bets of $220,000 and 1,115 bets of $110,000. He estimates Mickelson endured losses of approximately $100 million while betting more than $1 billion over the past three decades.

"The only other person I know who surpassed that kind of volume is me," Walters writes.

According to the book excerpts, in September 2012, Mickelson called Walters from Medinah Country Club during the 39th Ryder Cup and asked Walters to place a $400,000 wager for him on the U.S. team to win.

Walters responded by scolding Mickelson: "Have you lost your %&*$ing mind? Don't you remember what happened to Pete Rose? You're seen as the modern-day Arnold Palmer. You'd risk all that for this? I want no part of it."

Walters added that he didn't know whether Mickelson placed the bet elsewhere. The Americans lost the Ryder Cup to the Europeans by one point.

ESPN has reached out to Mickelson for comment.