Abu Dawud Book 11, Hadith Number 2877.

Chapter : If a nonmuslim who is at war with muslims dies and leaves a will and his heir embraces islam should he execute his testation.

Narated By Abdullah ibn Amr ibn al-‘As : Al-‘As ibn Wa’il left his will that a hundred slaves should be emancipated on his behalf. His son Hisham emancipated fifty slaves and his son Amr intended to emancipate the remaining fifty on his behalf, but he said: I should ask first the Apostle of Allah (PBUH). He, therefore, came to the Prophet (PBUH) and said: Apostle of Allah, my father left in his will that a hundred slaves should be emancipated on his behalf and Hisham has emancipated fifty on his behalf and fifty remain. Shall I emancipate them on his behalf? The Apostle of Allah (PBUH) said: Had he been a Muslim and you had emancipated slaves on his behalf, or given sadaqah on his behalf, or performed the pilgrimage, that would have reached him.