‘So when Jesus came he found that he had already been four days in the tomb.'
The time of four days is emphasised so as to demonstrate that Lazarus really was dead and his body probably beginning to decompose. Many Jews later believed that the spirit was retained within the body for three days after death before the body began to decompose. It is possible that this belief was already prevalent. If it was so the four days would be seen as sufficient to ensure that the spirit had left his body.