It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Holy Prophet (peace and blessings be upon him) said: Five prayers, and one Friday to the next Friday, and one Ramadan to the next Ramadan are expiation for the sins committed in between, provided that major sins are avoided.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 9197
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد حسن، م: 233 وهذا إسناد ضعیف، عمر بن إسحاق مجھول