FASTING CHAPTER · 51 – The Prohibition of Fasting Only on Saturdays
Yezid ibn Samman (may Allah be pleased with him) narrated:
The Messenger of Allah (peace and blessings upon him) said: “Do not fast on Saturday, except for obligatory fasts. If anyone among you does not find anything other than a grape seed or a branch from a tree [on that day], let him chew it [and break his fast].”
Abu Dawud said: This hadith is abrogated.