Apple Inc. co-founder Steve Jobs passed away three years ago, but current Apple CEO Tim Cook has had difficulty deleting Jobs from his iPhone contact list.

In a new book that is sympathetic to the often vilified Apple co-founder, Cook reveals that ever since Jobs died from pancreatic cancer, his number has lived on in Cook’s phone, according to an International Business Times report.

It is one anecdote in the book “Becoming Steve Jobs: The Evolution of a Reckless Upstart into a Visionary Leader.” It discusses what are described as untold stories about jobs based on interviews with friends and family, and Apple voluntarily participated in the biography since the author, Brent Schlender, was a close friend of Jobs who Apple believed would wants his legacy to be maintained.

John Lasseter, Pixar’s chief creative officer, was the one who revealed the Cook story, saying that he had approached the current CEO at a birthday party in 2013 and started talking to him. When the conversation turned to Jobs, Lasseter asked if Cook missed him, and Cook took out his phone and showed Jobs still in his contact list, saying he couldn’t bring himself to remove the number.

Cook apparently had once offered to donate part of his liver to help Jobs battle pancreatic cancer, according to the book.

A CNN report notes that the book works to “soften” the image of Jobs, who is often seen as an aggressive man not afraid to bulldoze over other people and behave cruelly, even verbally abusing other employees.

This book attempts to humanize him by discussing his more successful phases when his personality began to soften.

Although it is an unauthorized biography, Apple approved it in order to maintain Jobs’ legacy, especially in light of the reputation he has received after his death.

The book “Steve Jobs” by Walter Isaacson actually was an authorized biography, but Apple CEO Tim Cook hates the book, saying that it did Jobs “a tremendous disservice” and it “focused on small parts of his personality,” according to the CNN report.