Apple chief executive Tim Cook offered a part of his liver to a dying Steve Jobs, according to a new book due to be released this month.
The book, Becoming Steve Jobs, excerpts of which have been published online, throws light on life inside Apple as it grew into one of the world's most powerful technology companies.
It also charts the relationship between Mr Cook and Mr Jobs.
According to the book, Mr Jobs angrily turned down Mr Cook's offer.
In 2004, Mr Jobs announced that he was suffering from pancreatic cancer and by 2009, the Apple chief executive was very ill, unable to come into the office and waiting for a liver transplant.
Mr Cook regularly visited Mr Jobs at home and after one visit he "left the house feeling so upset that he had his own blood tested", according to excerpts published by Fast Company executive editor Rick Tetzeli, who co-authored the book.
Fellow author Brent Schlender is a journalist who interviewed Mr Jobs several times throughout his life.