It is narrated from Hazrat Hafsa that there are four things which the Prophet (peace be upon him) never abandoned: fasting on the tenth of Muharram, fasting during the ten days of Dhul-Hijjah, fasting three days in every month, and offering two rak'ahs before the Fajr prayer.
Hadith Referenceمسند احمد / مسند النساء / 26459
Hadith Gradingحکم دارالسلام:حديث ضعيف دون قوله: و الركعتين قبل الغداة، فصحيح، وفي هذا الإسناد أبو إسحاق الأشجعي، وهو مجهول