Avraham fell on his face and laughed, and said to himself, Can a child be born to a man a hundred years old…
Rashi on Genesis 17:17 — Abraham’s laughter is read through Onkelos as joy, contrasted with Sarah’s later laughter.
English: “And he laughed” — Onkelos renders this as joy; from this Rashi learns that Abraham believed and rejoiced.
Supplementary classical material not listed by Torah Temimah under this exact passuk.