When the Lord promised Abraham that at the appointed time, he would return to Abraham and Sarah his wife shall have a son, Sarah who heard this promised laughed within herself saying, “How shall she and her husband (whom she respectfully referred to as her lord) have this pleasure?” since she had gone past the age of child bearing. So for Sarah to have a child would be nothing short of a miracle.

Although some commentaries suggest that Sarah laughed out of astonishment and amusement, the Scripture only gives us insight to the fact that she laughed in a questioning manner – “How can this be?” for the Lord tells Abraham, “Why did Sarah laugh, saying shall I of a surety bear a child when I am old?” This is further corroborated by the fact that Sarah denies her laughter for she was afraid. However, you see the Lord question, but not rebuke Abraham or Sarah. Instead the Lord reveals to them a glimpse of his character – that he indeed is a miracle working God – making the barren fertile and that there is absolutely nothing that is too difficult for the Lord. Upon this revelation, I believe that Sarah believed in the promise coming true, for the Scripture records that through faith, Sarah in her old age, past her child bearing age, received strength and was able to bear a child, for she understood that the one who had promised is faithful (Hebrews 11:11)

Points to ponder:
When God reveals his plan for our life, we may find it astonishing, amusing, and even unbelieving, often evoking a natural human reaction and response to laugh within ourselves, but let us not fail to recognize like Sarah, that when God promises, it is an sure deal – a ‘Yes’ and ‘Amen’ for nothing is too hard for the Lord. This is not a laughing matter, but a matter of faith. Do you believe?

Genesis 18:10-15 (KJV)
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.

Hebrews 11:11 (KJV)
11 Through faith also Sara herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised.