كتاب الصيام
5  
Fasting
Bulugh al-Maram 674
And it's basic meaning is in Al-Bukhari and Muslim from the narration of Aisha (with the wording) "that Hamza bin 'Amro asked".
وَأَصْلُهُ فِي " اَلْمُتَّفَقِِ " مِنْ حَدِيثِ عَائِشَةَ; { أَنَّ حَمْزَةَ بْنَ عَمْرٍو سَأَلَ } 1
Reference : Bulugh al-Maram 674
In-book reference : Book 5, Hadith 674
English translation : Book 5, Hadith 695
Hadith Text
Reference