The note reads only:
Locke had earlier tried to convince Jack that he must stay on the Island ("Through the Looking Glass, Part 1") ("There's No Place Like Home, Part 3") and the two had a longstanding disagreement in philosophy with regards to science vs. faith.
Jack originally refused to read the note, putting it in Locke's casket after he put Christian's shoes on him while in Simon’s Butcher Shop. However, the note was given back to him on the plane by Rupa Krishnavani after it was found by the airline security when they were screening his cargo. Jack eventually read the note after a conversation with Ben in which Ben asked Jack if he blamed himself for Locke's suicide. After reading the note, the plane encountered turbulence and the plane was engulfed in a flash of white light. Jack then woke up on the Island.
Shortly after waking up, Jack looked at a fragment of the suicide note in his hand. Only the words "I wish" were legible. Jack discarded the fragment onto the ground. ("316")