The five (daily) prayers, Friday prayer to the next Friday prayer, and Ramadan to the next Ramadan are expiation of the sins committed between them, so long as major sins are avoided

The Prophet (may Allah's peace and blessings be upon him) informs us that the five prayers prescribed to be performed during the day and night, the Friday prayer every week, and the fasting of the month of Ramadan every year expiate minor sins committed between them, provided that major sins are avoided. As for major sins like adultery and alcoholic drinking, these can only be expiated by repentance.