1)
What did Sarah mean when she declared that whoever heard would laugh for her?
1.
Rashi #1 and Targum Onkelus: She meant that they would rejoice for her.
2.
Targum Yonasan and Rashbam: Whoever hears about the wondrous miracle of the birth of her son will be filled with a joy borne of amazement.
3.
Rashi #2: She was hinting at the abundance of laughter that resulted from the fact that, on that day, many barren women were blessed with a child, many sick people were cured and many prayers were answered.
4.
Seforno: Everyone would laugh for joy for her and forget their concern for the baby's pain (due to the Milah), because, in spite of the pain of the baby, HaSh-m had filled her heart with joy.
