Ata (may Allah have mercy on him) narrates that we were informed that they used to do the same: when they would begin the morning without fasting, until forenoon or after it, and perhaps they had found breakfast or perhaps not.
Hadith Referenceمسند الإمام الشافعي / كتاب الصيام / 643
Hadith Takhrijاسناده صحيح وهـو مـوصــول بالسند السابق : اخرجه البيهقي : 4 / 204 ۔ وفي المعرفة السنن والآثار له (2442) ۔ وعبدالرزاق (7776) وابن ابي شيبة (9106)، (9109)۔