Apple CEO Tim Cook offered to donate a portion of his liver to Steve Jobs when he was in need of a donor, Brent Schlender and Rick Tetzeli report in their book "Becoming Steve Jobs: The Revolution of a Reckless Upstart Into A Visionary Leader."

The book doesn't launch until March 24, but blog Cult of Mac was able to see some snippets early through Amazon's "Look Inside the Book" feature. Amazon has since blocked out most of the preview. Fast Company also saw spotted the excerpt.

Here's what Schlender and Rick Tetzeli wrote, according to Fast Company:

One afternoon, Cook left the house feeling so upset that he had his own blood tested. He found out that he, like Steve, had a rare blood type, and guessed that it might be the same. He started doing research, and learned that it is possible to transfer a portion of a living person’s liver to someone in need of a transplant. About 6,000 living-donor transplants are performed every year in the United States, and the rate of success for both donor and recipient is high. The liver is a regenerative organ. The portion transplanted into the recipient will grow to a functional size, and the portion of the liver that the donor gives up will also grow back.

But Jobs refused the offer, the book says. "He cut me off at the legs, almost before the words were out of my mouth," said Cook. "'No,' he said. 'I'll never let you do that. I'll never do that."

Here's the rest of the excerpt, via Fast Company:

Somebody that’s selfish," Cook continues, "doesn’t reply like that. I mean, here’s a guy, he’s dying, he’s very close to death because of his liver issue, and here’s someone healthy offering a way out. I said, ‘Steve, I’m perfectly healthy, I’ve been checked out. Here’s the medical report. I can do this and I’m not putting myself at risk, I’ll be fine.’ And he doesn’t think about it. It was not, ‘Are you sure you want to do this?’ It was not, ‘I’ll think about it.’ It was not, ‘Oh, the condition I’m in . . .’ It was, ‘No, I’m not doing that!’ He kind of popped up in bed and said that. And this was during a time when things were just terrible. Steve only yelled at me four or five times during the 13 years I knew him, and this was one of them."

According to Walter Isaacson's biography of Steve Jobs, which was published in 2011, Steve Jobs traveled to Memphis to receive his liver transplant. The operation extended his life by two-and-a-half years, as Memphis-based newspaper Commercial Appeal also reported.

We're expecting to learn more fascinating details about Jobs' life when the book launches later this month.