This week we read about the birth of Yitzchak and the laughter that surrounds it.
Both Avraham and Sarah when separately hearing about the expected birth, respond with laughter, and of course the child born is named Yitzchak, from the word "laughter" צחק.
Although the descriptions of Avraham and Sarah's response are quite similar, it seems that Hashem is angry with Sarah's laughter but not with Avraham's.
Why is that?
What's the difference between Sarah's laughter and Avraham's? Is laughing a good thing or a bad thing? And why is the child named after this laughter - יצחק?