(40) باب مَتَى يُقْضَى قَضَاءُ رَمَضَانَ
Narrated `Aisha:
Sometimes I missed some days of Ramadan, but could not fast in lieu of them except in the month of Sha'ban." Said Yahya, a sub-narrator, "She used to be busy serving the Prophet (ﷺ) ."
Reference: Sahih al-Bukhari 1950
In-book reference: Book 30, Hadith 57
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 31, Hadith 171