Genesis 1:14; Genesis 17:21; Genesis 18:14; Genesis 21:2

Genesis 1:14

14 Then God said, "Let there be lights in the expanse of the heavens to separate the day from the night, and let them be for signs and for seasons and for days and years;

Genesis 17:21

21 "But My covenant I will establish with Isaac, whom Sarah will bear to you at this season next year."

Genesis 18:14

14 "Is anything too difficult for the LORD ? At the appointed time I will return to you, at this time next year, and Sarah will have a son."

Genesis 21:2

2 So Sarah conceived and bore a son to Abraham in his old age, at the appointed time of which God had spoken to him.