Leonard Nimoy died at the age of 83 on Friday, and his funeral is tomorrow.
His friend and Star Trek costar William Shatner went on Twitter to express his sadness about not being able to attend the funeral service.
Shatner agreed to be at the Red Cross Ball tonight in Florida on Saturday night and can't make it back in time.
NEWS: Remembering Leonard Nimoy
After sharing his feelings, he asks to remember his friend on Sunday and reminds everyone how much he loved Nimoy.
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Nimoy passed away at his Bel-Air home. According to the actor's wife, Susan Bay Nimoy, her husband's passing was due to the end stages of chronic obstructive pulmonary disease (CPOD).
Nimoy sent out his final tweet about life on Feb. 23.
Watch the video below to remember Nimoy and see how the character of Spock changed him.