Prayer (Kitab Al-Salat): Details of Commencing Prayer
Dawud :: Book 3 : Hadith 1181
Narrated Qabisah al-Hilali:
There was an eclipse of the sun in the time of the Apostle of Allah (peace_be_upon_him). He came out bewildered pulling his garment, and I was in his company at Medina. He prayed two rak'ahs and stood for a long time in them. He then departed and the sun became bright. He then said: There are the signs by means of which Allah, the Exalted, produces dread (in His servants). When you see anything of this nature, then pray as you are praying a fresh obligatory prayer.