Have you ever prepared for a visit from a guest and they ended up not showing up? There was a lot of preparation involved: cleaning, cooking, etc. Then the guest never shows up. How does that make you feel? Have you, as a leader, ever given someone a task to do and they did not get it done as expected? Do you ever feel like you must do everything because you cannot trust anyone else to do the job? We have all experienced disappointments and broken promises. We have all depended on someone, only to have them let us down. Though we may struggle in keeping our promises to one another, God never breaks His promises. In addition to never breaking a promise, He also gives us just exactly what we need the moment we need it. As we study the events in Genesis 21, we see several spiritual nuggets that points to the fact that we can always rely on God.
The Lord did as He had spoken (v. 1-2). For many years, Sarah and Abraham heard God’s promise that they would have a child. Abraham was told on multiple occasions that he would receive a great land and would become a great nation. Both Abraham and Sarah struggled with this promises over the years. At one point they took matters in their own hands by having a child through Sarah’s maidservant. In another instance they laughed mockingly as they were told that they would have a child in their old age. They must have thought that God had forgotten them. Yet, at just the right time, Sarah conceived and had a son. God kept His promise. God always keeps His promises. He has made many and great promises to us in His Word. We can be confident of the fact that if God says it, then it is a done deal. God always does what He says He will do.
God hath made me laugh (v. 6). The laughter seen in verse six is not the same laughter seen earlier when Sarah doubted God’s promise. This was not a sarcastic laugh. It was a laughter of joy. Sarah was so overwhelmed by what God had done, that she could not help but laugh. What a sign of spiritual health laughter can be! Not laughter at the contrived levity that we call comedy—but a laughter that says, with Sarah, “Ha! I can hardly believe how good God has been to me!” Do you ever laugh like that? If not, is it a sign that, perhaps, your successes are not results of the surprising grace of God but simply of the run-of-the-mill paybacks of worldly wisdom? When God does something good for us, when He provides, when we see His promises fulfilled; it should cause us to swell up with joy in such a way that we laugh with joy.
And God Said (v. 12). Naturally, after the birth of Isaac, there was tension between Sarah and Hagar. With the birth of Isaac, Ishmael no longer laid any claim to an inheritance from Abraham. As a result, Sarah wanted Abraham to cast Hagar and her son out. This troubled Abraham, but God spoke. God encourages Abraham to not worry about the situation and that Hagar and Ishmael would be taken care of. God has a way of intervening in our lives at just the right moment. He always knows the right thing to say. If we learn to follow His way and listen to His voice then we will never be lost. God speaks to us today through His written Word and through other godly men and women that we can trust. My friend, when God speaks to us we must listen. He always knows what is best and He always has His best for us in mind.
And God Heard (v. 17). God heard the cry of Ishmael. We serve a God who hears. He hears not just the words we say, but He hears our every thought. To hear is not just to hear with your ears, but it is to hear with your heart. It is to understand. God understands us. He understands us even when we do not understand ourselves. He knows how you feel. He knows your struggles. He knows what troubles you. When you call out to Him, He listens and He is filled with compassion.
And God opened (v. 19). When Hagar was in total despair and did not know what to do, God opened her eyes. Many times in our lives God has already provided for us, but we cannot see it. We are so focused on our circumstance that we miss seeing what God is doing. My friend, God has a well of water for you. Just open your eyes and see what God has done.
In the concluding verses of this chapter we see a covenant made between Abraham and Abimelech. This covenant serves as a reminder that God always provides and that His Word is sure. Whatever you may be going through, remember, God always keeps His promises and He always provides.
 Strassner, K. (2009). Opening up Genesis (p. 92). Leominster: Day One Publications.