بُلُوغُ الْمَرَامِ
Bulugh al-Maram 487
The Book of Prayer
وَعَنْ أَنَسٍ - رضى الله عنه - قَالَ: { كَانَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -لَا يَغْدُو يَوْمَ اَلْفِطْرِ حَتَّى يَأْكُلَ تَمَرَاتٍ } أَخْرَجَهُ اَلْبُخَارِيُّ [1] .
Narrated Anas (RA): Allah's Messenger (ﷺ) would not go out on the day of the breaking of the fast till he ate some dates, which he used to eat in odd numbers. [al-Bukhari reported it].
Sunnah.com reference: Book 2, Hadith 412