Here is Quranic verse for it, aswell as Ibn Kathir commentary
Quran 65:4
As for your women past the age of menstruation, in case you do not know, their waiting period is three months,
and those who have not menstruated as well. As for those who are pregnant, their waiting period ends with delivery.1 And whoever is mindful of Allah, He will make their matters easy for them.
Here is Ibn Kathir commentary on it
"(4. Those in menopause among your women, for them the `Iddah, if you have doubt, is three months; and for those who have no courses. And for those who are pregnant, their `Iddah is until they lay down their burden; and whosoever has Taqwa of Allah, He will make his matter easy for him.) (5. That is the command of Allah, which He has sent down to you; and whosoever has Taqwa of Allah, He will expiate from him his sins, and will increase his reward.)
Allah the Exalted clarifies the waiting period of the woman in menopause.
And that is the one whose menstruation has stopped due to her older age. Her `Iddah is three months instead of the three monthly cycles for those who menstruate, which is based upon the Ayah in (Surat) Al-Baqarah. (see 2:228) The same for the young, who have not reached the years of menstruation. Their `Iddah is three months like those in menopause. This is the meaning of His saying;
QTafsir Tafsir Ibn Kathir Mobile
QTafsir Tafsir Ibn Kathir Mobile
Either case. That doesnt take away child marriage of Aisha, but just context here