Genesis 15:3 And Abram said, “You have given me no children; so a servant in my household will be my heir.”
How well do you listen to God? It is very difficult to listen when He tells you something which you think is difficult to hear!
Abraham and Sarah were well past the normal age of child bearing, and yet God was telling them they were going to have a child; what they did was try to hurry God along by helping out in their own way.
God does not need us to help Him make decisions, to help Him change things He has already said will happen or to stop things He has said will stop.
Stop and wait on God…