Abu Bakr bin 'Ayyash al-Asadi أبو بكر بن عياش بن سالم الأسدي · The Book of Fasting

" I heard the Messenger of Allah say: 'The month is twenty-nine days."'

"We are an unlettered Ummah, we do not use astronomical counting or computation. The month is like this, and this, and this," he did three times, showing it as twenty-nine.