Zar bin Habaysh bin Habasha زر بن حبيش بن حباشة · 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.

"The Messenger of Allah said; 'Take Sahur, for in Sahur there is blessing.""

"Eat Sahur, for in Sahur there is blessing." (Sahih Mawquf) while Ibn Abi Laila narrated it in Marfu form:

"The Messenger of Allah used to be keen to fast on Mondays and Thursday."