Genesis 18:1-15 KJV
1 And the LORD appeared unto him in the plains of Mamre: and he sat in the tent door in the heat of the day;
2 And he lift up his eyes and looked, and, lo, three men stood by him: and when he saw them, he ran to meet them from the tent door, and bowed himself toward the ground,
3 And said, My Lord, if now I have found favour in thy sight, pass not away, I pray thee, from thy servant:
4 Let a little water, I pray you, be fetched, and wash your feet, and rest yourselves under the tree:
5 And I will fetch a morsel of bread, and comfort ye your hearts; after that ye shall pass on: for therefore are ye come to your servant. And they said, So do, as thou hast said.
6 And Abraham hastened into the tent unto Sarah, and said, Make ready quickly three measures of fine meal, knead it, and make cakes upon the hearth.
7 And Abraham ran unto the herd, and fetcht a calf tender and good, and gave it unto a young man; and he hasted to dress it.
8 And he took butter, and milk, and the calf which he had dressed, and set it before them; and he stood by them under the tree, and they did eat.
9 And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent.
10 And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him.
11 Now Abraham and Sarah were old and well stricken in age; and it ceased to be with Sarah after the manner of women.
12 Therefore Sarah laughed within herself, saying, After I am waxed old shall I have pleasure, my lord being old also?
13 And the LORD said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, which am old?
14 Is any thing too hard for the LORD? At the time appointed I will return unto thee, according to the time of life, and Sarah shall have a son.
15 Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh.

A woman of faith following her husband instruction despite the consequences of his instruction to protect her husband Abraham. Oops! That is another story or is it. We got to remember God promised Abraham would have offspring and they be as numberous as the stars. Abraham was a Shepherd/herdsmen. He and his wife probably watching animals knew more about birthing babies and how they were made but Sarah had given at one point her maid to him and she bore a son and Sarah was jealous. Yet she had twice in her life lied two different kings that she was married and claim she was his sister though they were married. They both shared one parent and they had different mothers. Both times she was confronted of her lie, one time God gave the king a dream and the other time King saw Abraham tenderly caressing her. Sarah would then get out of being almost married to a king. Now Abraham was having Sarah preparing God a meal for him and two angels that came to speak to Abraham about Sodom and Gomorah's day of destruction. As the meal was being prepare God told Abraham in a year he have a male heir from Sarah womb. Sarah not out of disrespect could no longer contain herself but laughed because she was past child bearing years.

Truth when she gave birth to Isaac she was eighty years old. God asked why did she laugh and it because of her age but she tried to deny her laughter. God said he would return and she would conceive and bear Abraham an offspring. For nothing was impossible for God. A year later it happen to her as God had told Abraham.

Did Sarah have trouble believing? Probably like many skeptics but if you believe God's word it did happen.They fact it happen would cause Abraham to send Sarah maid away for showing his son of his wife disrespect and his wife as well.

Sarah was virtuous woman, but by tradition her prenancy was unusual. If God told you something would happen then a person can rest in who God is. He is the God of Possibilities despite what scienve or man has figured was impossible.

Dear Heavenly Father help us to trust your word because you are a God of possibilities. In Jesus precious name, Amen.

Continual Scripture Study: Genesis 21:1-7 KJV
1 And the LORD visited Sarah as he had said, and the LORD did unto Sarah as he had spoken.
2 For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him.
3 And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac.
4 And Abraham circumcised his son Isaac being eight days old, as God had commanded him.
5 And Abraham was an hundred years old, when his son Isaac was born unto him.
6 And Sarah said, God hath made me to laugh, so that all that hear will laugh with me.
7 And she said, Who would have said unto Abraham, that Sarah should have given children suck? for I have born him a son in his old age.