In Islam fasting is required during Ramadan, the ninth month of the Muslim lunar calendar, during which all Muslims are required to abstain during daylight hours from eating, drinking, or engaging in sexual activity. Through heightened awareness of their bodily needs, Muslims come to greater awareness of the presence of God and acknowledge gratitude for God's provisions in their lives. Abstinence during Ramadan is required of all Muslims, except children, those who are ill or too elderly, those who are traveling, and women who are menstruating, have just given birth, or are breastfeeding. In such cases, one may make up days of fasting at a later time. Various traditions recommend voluntary fasting: the fast of Ashura (tenth day of the month of Muharram); fasting for six days in Shawwal, the month after Ramadan; fasting three days of each month; and fasting on Mondays and Thursdays. Expiatory fasting (kaffarah) atones for certain transgressions or compensates for omissions of duty; fasts may be undertaken for failing to fulfill an oath (see Quran 5:89, 58:4) or the accidental killing of a believer (4:92). Some Sufis undergo fasts as part of their spiritual exercises.