I have been recommended the following book:
A gift for the bereaved Parent. by Zamir Hussain.
Its a lovely compilation of quotes from the Qu'ran and Hadiths to help those parents that have lost their children.
One of the the most touching parts of the book is the letter of condolence which was sent by the Prophet (pbuh)
to Mu'ad ibn Jabal (RA) upon the death of Mu'ad's son.
In which the Prophet of Allah says " Your son was a special trust from Allah. He blessed you with him till he desired and took him away
from you in return for a Great Reward...."
Jazak'Allah Khair.