Shahih
Bab Perkataan Nabi ﷺ: 'Jika kalian melihat hilal, maka berpuasalah, dan jika kalian melihatnya, maka berbukalah'
Allah's Messenger (ﷺ) said, "The month (can be) 29 nights (i.e. days), and do not fast till you see the moon, and if the sky is overcast, then complete Sha'ban as thirty days."