A female companion (may Allah be pleased with her) asked the Prophet (peace and blessings be upon him) about the ruling of fasting on Saturday, so the Prophet (peace and blessings be upon him) said: "There is neither any special reward for it nor any sin."
Hadith Referenceمسند احمد / مسند النساء / 27074
Hadith Gradingحکم دارالسلام:إسناده ضعيف لضعف ابن لهيعة، وقد تفرد به، واختلف فيه على ابن لهيعة