Sahih Muslim Book 32, Hadith Number 6371.

Chapter : The merit of one who resigns himself to the will of God calmly at the time of the death of one’s son.

Abu Huraira reported that a woman came to Allah’s Apostle (may peace be upon him) with her child and said: Allah’s Apostle, invoke Allah’s blessing upon him for I have already buried three. He said: You have buried three! She said: Yes. Thereupon he (the Holy Prophet) said: You have, indeed, safeguarded yourself against the torment of Hell with a strong safeguard. ‘Umar has made a mention of his father, whereas others have not made a mention of his father.