Genesis 16
In chapter 16 we see Sarai's struggle with God's timing and her own barrenness. It's been 10 years since they began to dwell in Canaan and Sarai is not getting any younger. She seems to have come to the conclusion that God's plan for this Seed who was to come doesn't involve her. Many times when God doesn't move in our lives according to our timeline, we begin to take matters into our own hands. This passage would warn us otherwise.
Despite Abram and Sarai's faultering, God demonstrates His care and compassion for their Egyptian slave who is now pregnant and has now run away doesn't know what to do. The Angel of the LORD meets Hagar on her way back to Egypt and instucts her to go back and submit herself under the hand of her mistress Sarai. He sends her back however with a heart filled with hope in the promises that He made her.