It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The five obligatory prayers and from one Friday to the next Friday are an expiation for the sins committed in between, as long as major sins are not committed."
Hadith Referenceصحيح ابن خزيمه / كتاب: الصلاة / 314