Genesis 17:17

17:17 Then Abraham bowed down with his face to the ground and laughed ¹  as he said to himself, ²  “Can ³  a son be born to a man who is a hundred years old? ⁴  Can Sarah ⁵  bear a child at the age of ninety?” ⁶ 

Genesis 17:24

17:24 Now Abraham was 99 years old ⁷  when he was circumcised; ⁸ 

[17:17]  ¹ sn Laughed. The Hebrew verb used here provides the basis for the naming of Isaac: “And he laughed” is וַיִּצְחָק (vayyitskhaq); the name “Isaac” is יִצְחָק (yitskhaq), “he laughs.” Abraham’s (and Sarah’s, see 18:12) laughter signals disbelief, but when the boy is born, the laughter signals surprise and joy.

[17:17]  ² tn Heb “And he fell on his face and laughed and said in his heart.”

[17:17]  ³ tn The imperfect verbal form here carries a potential nuance, as it expresses the disbelief of Abraham.

[17:17]  ⁴ tn Heb “to the son of a hundred years.”

[17:17]  ⁵ sn It is important to note that even though Abraham staggers at the announcement of the birth of a son, finding it almost too incredible, he nonetheless calls his wife Sarah, the new name given to remind him of the promise of God (v. 15).

[17:17]  ⁶ tn Heb “the daughter of ninety years.”

[17:24]  ⁷ tn Heb “the son of ninety-nine years.”

[17:24]  ⁸ tn Heb “circumcised in the flesh of his foreskin” (also in v. 25).