The stone slipped a little but not enough to let them get out. Similarly, the second and the third man mentioned an act of goodness and prayed to God to shift the stone. The stone slipped down and the entry to the cave opened up. So the men got out. This story shows how service to one's parents leads to blessings from God and rescue from troubles.
All parents are well wishers of children.
So it is the duty of children to obey their orders and act accordingly. Some children listen to parental orders but do not act upon these or show laziness in carrying out these orders.