Genesis 16 is a lesson to us all. God had made a promise to Abram. That promise was going to take a miracle. There was no way it was humanly possible for Sarai to have a baby at her age. Yet God had told Abram that he would have a son. This could be seen as an opportunity, rejection, or false promise.
It could be a false promise (or disillusion) in that either God did say or Abram only thought He said, and that there was no real plan for the fulfillment of the promise.
It could be that God was going to bring it to fulfillment, and simply had not yet (which we know to be the truth). However, that seemed less and less likely every day.
Finally, it could be a rejection. God could have been making the promise to Abram while rejecting Sarai. This was likely the struggle that Sarai was going through. She was past the age of child birth, but Abram was not. She could not have children, but her husband still could. The promise had been made to him and not to her. He needed an heir, and she couldn’t provide it. So she did what she felt needed to be done to fulfill God’s promise for Him… and it was the wrong thing.
In Sarai’s defense, as far as we know, there had never been a single woman past the age of childbearing who had miraculously conceived. It was unheard of. Is that a valid excuse? No, not really, but it does explain her decisions. She knew what her husband and family needed. She knew she couldn’t provide it, so she did what she thought was the only feasible solution… and it backfired on her.
It also wasn’t fully her fault either. Abram listened to the voice of Sarai. He accepted her assessment and solution.
Ultimately though, the question comes back to us. What promises that God has made to us are we trying to fulfill of our own power? Are we trying to “help” God fulfill His promises, or are we resting in the promises of the God who promises and fulfills?