‏الصيام : Hadeeth No:2369 'Abdullah b. Umar (Allaah be pleased with both of them) reported Allaah's Measenger (sallAllaahu alayhi wa sallam) as saying: When you see the new moon, observe fast, and when you see it (again) then break it, and if the sky is cloudy for you, then calculate it....

‏الإيمان : Hadeeth No:143 A hadith like this as narrated by Ibn 'Umar has also been transmitted by Abu Huraira....