Silsilat al-Ahadith al-Sahihah

Ubaid A’raj says: My grandmother narrated to me that she went to the Messenger of Allah (peace and blessings be upon him) while he was having lunch; it was a Saturday. The Prophet (peace and blessings be upon him) said: “Come, eat food.” She said: I am fasting. The Prophet (peace and blessings be upon him) said: “Did you fast yesterday?” She said: No. The Prophet (peace and blessings be upon him) said: “Then eat food, for you will get neither reward nor punishment for fasting only on Saturday.”