Episode 21: Fasting Ramadan should necessarily be commenced with the sight of the new moon and finished with the sight of the new moon.
Ibn Umar (may
Allah be pleased with both of them) reported Allah's Messenger (peace and
blessings be upon him) as saying: The month of Ramadan may consist of
twenty−nine days. So do not fast till you have sighted it (the new moon) and do
not break fast, till you have sighted it (the new moon of Shawwal), and if the
sky is cloudy for you, then calculate it (and complete thirty days).
It was related by Muslim.