(a) Ikrimah (may Allah have mercy on him) said: It was said to Ibn Abbas (may Allah be pleased with them both) that such-and-such wife of the Prophet (peace and blessings be upon him) had died, and he fell down in prostration. It was said: Do you prostrate at this time? He said: The Prophet (peace and blessings be upon him) said: "When you see a sign, then prostrate." And what sign could be greater than the passing away of the wives of the Prophet (peace and blessings be upon him)?
(b) In the narration of al-Qadi it says: We heard a cry in Madinah, and Ibn Abbas (may Allah be pleased with them both) said to me: O Ikrimah! Go and see what this cry is. He said: I went and found that Sayyidah Safiyyah bint Huyayy (may Allah be pleased with her), the wife of the Prophet (peace and blessings be upon him), had died.
He said: I came to Ibn Abbas (may Allah be pleased with them both) and found him in prostration, although the sun had not yet risen.
I said: Subhan Allah! The sun has not yet risen, and you have already prostrated! He said: Did the Prophet (peace and blessings be upon him) not say: "When you see a sign, then prostrate"? So what sign could be greater than that the Mothers of the Believers are departing from among us while we remain alive?
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخسوف / 6379