Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.020.

The scholars consider it desirable that the deceased’s family, friends, and other good people be informed about his death, so that they may share in the reward of participating in his funeral. It is reported in Sihah Sittah on the authority of Abu Hurairah that the Prophet, peace be upon him, informed his companions about the death of Negus (Najashi), the King of Abyssinia, the day that he passed away. And then the Prophet, peace be upon him, led them to the prayer ground where he lined them up and offered funeral prayer (for him) with four takbirs.

Ahmad and Bukhari narrate from Anas that the Prophet, peace be upon him, informed the people about the death of his companions, Zaid, J’afar, and Ibn Rawahah, commanders of the Muslim army in the Battle of Mu’ tah, before they received any news from the battlefield. Tirmizhi observes that there is no harm in informing the family and close relations of the deceased person about his death. Al-Baihaqi says he was told that Malik ibn Anas disliked announcing someone’s death at the gates of the mosque, but found nothing wrong with going around inside the mosque to the various groups of students there and informing them of someone’s death.

A report, recorded by Ahmad and Tirmizhi on the authority of Huzhaifah, says that Huzhaifah said: “When I pass away, let no one vex me, for I am afraid (my death will be announced) and it may be regarded (as an invitation to) mourning. And I heard that the Prophet, peace be upon him, forbade announcing the death of a person as an invitation to mourning. This refers to a practice of the pre-Islamic period. In those days when a noble died they would send a horseman to various tribes to inform them about his death saying: ‘The people are devastated on account of the death of so and so.’ Such an announcement was (always) accompanied by crying and weeping.”