Sahih Muslim
The Book of Fasting (Kitab Al-Sawm)
Book Number: 006 / Hadith Number: 2377
Sa'd b. 'Ubaida reported that Ibn'Umar (Allah be pleased with both of them) heard a person saying: This night is the midnight (of the month). Upon this he said to him: How do you know that it is the midnight (of the month), for I heard the Mes- senger of Allah (may peace be upon him) as saying: The month is thus and thus (and he pointed with his ten fingers twice) and thus (i. e. at the third time he pointed with all his fingers but withdrew or folded his thumb)?