The Book of Fasting
كتاب الصيام
Read the English translation first, with the original Arabic directly underneath.
If a fasting person is invited to eat and he does not want to break his fast, or someone insults him or argues with him, it is recommended for him to say: "I am Fasting", and he should protect his fast from obscene speech, ignorance and the like
Abu Zubair is reported to have heard Jabir b. 'Abdullah (Allah be pleased with both of them) as saying:
The Messenger of Allah (ﷺ) separated himself from his wives for a month. (His wives said: ) He came to us on the morning of the twenty-ninth. Upon this some, of the people said: It is the morning of twenty- ninth (according to our calculation). Upon this the Messenger of Allah (ﷺ) said: The month. may also consist of twenty-nine days. The Messenger of Allah (ﷺ) then flapped his bands thrice, twice with all the fingers of both his hand (to indicate twenty-nine) and by the third time with nine (fingers).
إِنَّ الشَّهْرَ يَكُونُ تِسْعًا وَعِشْرِينَ