What should I say when I hear the death of a Muslim? Is there any specific dua/words that Shahaba (R) uttered?
The prophet PBUH said:
إذا مات الإنسان انقطع عنه عمله إلا من ثلاثة : صدقة جارية . أو علم ينتفع به . أو ولد صالح يدعو له "صحيح مسلم 1613
If a person dies, his deeds are cut except for three: A running Charity (Ex: you helped build a Mosque, charity, etc..) or knowledge being used (Ex: you made a cure to help the sick) or a pious son to make dua for him. Please note that the last doesn't specifically mean an actual son, it can be anyone.
(Sahih Muslim 1613)
Given that, you can make Dua in any way you want or say anything. The prophet said a few Dua himself like (keep in mind that you can say anything you want):
عن أبي عبد الرحمن عوف بن مالك رضي الله عنه قال:(صلى رسول الله صلى الله عليه وسلم على جنازة فحفظت من دعائه وهو يقول: اللهم اغفر له وارحمه، وعافه واعف عنه، وأكرم نزله، ووسع مدخله، واغسله بالماء والثلج والبرد، ونقه من الخطايا كما نقيت الثوب الأبيض من الدنس، وأبدله داراً خيراً من داره، وأهلاً خيراً من أهله، وزوجاً خيراً من زوجه، وأدخله الجنة، وأعذه من عذاب القبر ومن عذاب النار ) صحيح مسلم 1912
Reported from father of Abdulrahaman ben awf be malik: The prophet PBUH prayed on a funeral and I remember some sayings of the prophet: Oh Allah have mercy on him, make him well and forgive him, make his decent honorable, make his space vast, wash him with water, ice and snow, and clear him of his sins like cleaning a white shirt from dirt, and give him a house better than his house, a family better than his family, a wife better than his wife and give him paradise and to avoid the torture of the grave and hellfire.
Extracting from this ayah...
Who, when disaster strikes them, say, "Indeed we belong to Allah , and indeed to Him we will return."(Qur'an 2:156)
our interesting part....
"Indeed we belong to Allah , and indeed to Him we will return."... reciting this part in a language which you understand (say, ur mother tongue) is better.
And of course, along side, we pray for the deceased that Allah may forgive his/her sins and grant mercy on him/her.
May the creator guide us all.
Briefly speaking, whenever we hear that for example somebody died, the best dua/words seems to be according to the following words:
For a lady who dies, you say "Allah yirhama (Yarhamha)" (الله یرحمها) which in fact means May Allah bless her soul.
And for a man who dies, you say "Allah yirhamou"(Yarhamah) (الله یرحمه) which means May Allah bless his soul.