Dora Bas Rivka Silver O'H
Three days later, as Avraham was recuperating from his surgery, G-d paid him a visit. As G-d was speaking with Avraham, the latter saw three travelers a short distance away. Avraham asked G-d if he might excuse himself to go perform the mitzvah of hospitality to guests. G-d apparently acceding to this request, Avraham ran after the travelers and invited them to his tent for food and rest. Avraham instructed his household to prepare the finest flour into bread and to prepare a calf. He served his guests milk and other dairy foods, followed by the calf.
The guests asked where Avraham's wife Sarah was; he replied that she was in the tent. (They did this to point out her modesty to Avraham and make him appreciate her for it.) It turns out the guests were angels, each with a mission. The mission of the first was to announce that a year later, Sarah would have a baby. Sarah overheard and, this time, it was she who laughed. (Unlike Avraham, who had laughed with joy, Sarah laughed at the thought of it because she and Avraham were too old to have children.)
G-d spoke to Avraham and told him that Sarah shouldn't laugh because nothing is beyond Him. (When G-d spoke to Avraham, He only told him that Sarah said that she was too old; He omitted the part where she said Avraham was old, in order to spare his feelings. From this, we derive important lessons about shalom bayis, how to maintain peace in the home.)