Narrated Abu Hurairah [radiyallaahu-anhu]: Allaah’s Messenger (sallal-laahu-alayhi-wasallam) said, ”Allaah says, ‘I have nothing to give but Paradise as a reward to my slave, a true believer of Islamic Monotheism, who, if I cause his dear friend amongst the people of the earth to die, remains patience and hopes for Allaah’s reward.’ 
Imaam Abdul-Azeez Bin Baaz (rahimahullaah) said: ‘Dear friend: This means his beloved one, brother, father or wife. If he remains patient and hopes for Allaah’s reward, he will receive [the reward] of Paradise.
Saheeh Al-Bukhaari : hadeeth Number 6423]
 [Al-Hulalul Ibreeziyyah Vol 4. Page: 226. Footnote 4]