Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1987
Abu Mas'ud al-Ansari reported Allah's Messenger (may peace be upon him) as saying: Verily the sun and the moon are the two signs among the signs of Allah by which He frightens his servants and they do not eclipse on account of the death of any one of the people. So when you see anything about them, observe prayer, supplicate Allah till it is cleared from you.