John 20:9

For as yet they knew not the scripture, that he must rise again from the dead. So the disciples went away again unto their own home.

Jesus had repeatedly prophesied his resurrection; but until that moment they had not comprehended that he would actually come out of the grave. Until that moment, they did not really know it. The impact of this miracle was great enough to overcome all prior unbelief. They did not initiate a search for the body; they now knew he was alive! Thus their conduct confirmed their faith that he had risen. Moreover, their conduct throughout life afterward never deviated from the pattern established here. In all the years to come, their every word, deed, and thought proved the absolute certainty of their belief. They went to death shouting, "He is risen!"