It is narrated from Hazrat Aisha (may Allah be pleased with her) that during the time of the Prophet (peace and blessings be upon him), when our "days" would come, we would not make up (the missed fasts), nor were we ordered to make them up.
Hadith Referenceمسند احمد / مسند النساء / 25543
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد ضعيف لأجل ليث