Genesis 16:2 KJV
And Sarai said unto Abram, Behold now, the LORD hath restrained me from bearing: I pray thee, go in unto my maid; it may be that I may obtain children by her. And Abram hearkened to the voice of Sarai.
Someone has said that the more things change the more they remain the same.
Sarai does what is the typical thing for a human; she credits God with keeping from her what she wants and devises a plan to get it without God. One would think that if she was aware it was God who had restrained her she would submit to God for either His will or His future blessing. Knowing it was God who had kept her from having this child, should have been sufficient to convince her to trust God to keep His promises in other ways.
Contriving plans to get what we want against the plan of God has never led to any good thing.
God can restrain but Abraham and Sarah will learn soon, He is as capable of giving as He is of restraining.
And when God gives He adds no sorrow with it.