It is narrated from Hazrat Ibn Umar (may Allah be pleased with them) that the Prophet (peace and blessings be upon him) said: "A month consists of 29 days." People mentioned this to Hazrat Aisha (may Allah be pleased with her), so she said: "May Allah forgive Abu Abdur Rahman, he has made a mistake. In fact, the Prophet (peace and blessings be upon him) said: 'Sometimes a month is also of 29 days.'"