Jesus died after 15:00 on the Friday (Mark 15:33). Three hours later would be sunset (18:00). The Jewish Sabbath lasted from sunset on the Friday until sunset on the Saturday. Old Testament law specified that a corpse must not be allowed to hang on a tree beyond sundown (Deuteronomy 21:23) and Sabbath laws meant that any kind of work, including burial, would be prohibited.1
This means that Jesus’ body needs to be taken from the cross and buried before sunset, otherwise he would have no burial and his body would simply be discarded with that of the other criminals crucified next to him.
42 And when evening had come, since it was the day of Preparation, that is, the day before the Sabbath,