Rashi on Genesis 18:14/רש"י על בראשית י״ח:י״ד

1היפלא IS TOO HARD? — As the Targum takes it: is anything hidden — far distant and apart (מופלא) from Me that I cannot do as I would wish?

2למועד AT THE APPOINTED TIME — at the special time that I fixed for you yesterday (i.e. on a previous occasion) when I said, (17:21) “at this set time next year”.