Genesis 17

The translation of Moses's records suggests that as the Lord tells Abraham -

"...As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be.
16 And I will bless her, and give thee a son also of her: yea, I will bless her, and she shall be a mother of nations; kings of people shall be of her.
17 Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear?"  (Old Testament | Genesis 17:15 - 17)

The record that Abraham laughed and even questioned the Lord seem so contrary to the faithful Abraham we come to know in the scriptures.  In the JST of the Bible, the translation seems more like the Abraham we had come to know as we read -

"Then Abraham fell upon his face and rejoiced, and said in his heart, There shall a child be born unto him that is an hundred years old, and Sarah that is ninety years old shall bear."  (JST - Genesis 17:24)

I believe the word "laughed" was miss translated. 

There was something else I noticed in my reading -

"...Abraham said unto God, O that Ishmael might live before thee!
19 And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.
20 And as for Ishmael, I have heard thee: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation.
21 But my covenant will I establish with Isaac, which Sarah shall bear unto thee at this set time in the next year."  (Old Testament | Genesis 17:18 - 21)

There is no question in my mind that Abraham loved Ishmael just as much as he loved Isaac.  His greatest desire was that Ishmael would live or live righteously.  Thus the promises were great that he also would have a great posterity or nation.  And if they lived righteously, eternal blessings would be just as great as they would be for Isaac.  But not necessaril knowing exactly the mind and will of the Lord and purpose, it was through Isaac that the responsibility would be placed upon his posterity to bless all nations in the latter days with the priesthood and missionary work.  This was not to be the calling and burden of Ishmael.