Saying Inna lillahi wa inna ilayhi rajiun and when to say it

Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "My Ummah has been given something that has not been given to any other nation: reciting 'Inna lillahi wa inna ilayhi raji'un (We belong to Allah and to Him we return)' at the time of calamity."
Imam al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains a narrator, Muhammad bin Khalid al-Tahhan, and he is da'if (weak).

Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) explains regarding this statement of Allah Almighty: (Allah, the Exalted, says:) "Those who, when a calamity befalls them, say: Indeed we belong to Allah, and indeed to Him we shall return. It is they upon whom are blessings and mercy from their Lord, and it is they who are the rightly guided." Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) says: Allah Almighty has informed that when the believer submits to the command of Allah Almighty and recites 'Inna lillahi wa inna ilayhi raji'un (We belong to Allah and to Him we return)' at the time of calamity, three good things are recorded for him: blessings and mercy from Allah Almighty, and the realisation of the path of guidance. The Prophet (peace and blessings be upon him) said: "Whoever recites 'Inna lillahi wa inna ilayhi raji'un' at the time of calamity, Allah Almighty compensates him for his calamity (or repairs the harm caused by it), makes his outcome good, and gives him in its place something with which he is pleased."
Imam al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains a narrator, Ali bin Abi Talhah, and he is da'if (weak).

Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Death has its alarm. When one of you comes upon the death of his brother, he should say: 'Indeed we belong to Allah, and indeed to Him we shall return, and indeed to our Lord we shall be turned back. O Allah! Record him among the doers of good, place his record in Illiyyin, and be the caretaker in his place among those who come after him. O Allah! Do not deprive us of his reward, and do not put us to trial after him.'"
Imam al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains a narrator, Qays bin al-Rabi' al-Asadi, and he has been criticised.

Sayyiduna Imam Husayn bin Ali (may Allah be pleased with them both) narrates: I heard the Prophet (peace and blessings be upon him) say: "Any Muslim man or Muslim woman who is struck by a calamity, and then remembers it, even if it was long ago, and then is moved to recite 'Inna lillahi wa inna ilayhi raji'un', Allah Almighty grants him reward anew for it, and gives him that reward as on the day the calamity befell him."
Imam al-Tabarani recorded it in al-Mu'jam al-Awsat. Its chain contains a narrator, Hisham bin Ziyad Abu al-Miqdam, and he is da'if (weak).

Sayyiduna Abu Umamah (may Allah be pleased with him) narrates: We were going along with the Prophet (peace and blessings be upon him). The sandal strap of the Prophet (peace and blessings be upon him) broke, and he recited 'Inna lillahi wa inna ilayhi raji'un'. A man said to him: "This is for a sandal strap?" He said: "This too is a calamity."
Imam al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains a narrator, al-Ala' bin Kathir, and he is matruk (abandoned).

Sayyiduna Abu Umamah (may Allah be pleased with him) narrates: The sandal strap of the Prophet (peace and blessings be upon him) broke, and he recited 'Inna lillahi wa inna ilayhi raji'un'. The people said: "O Messenger of Allah! Is this also a calamity?" The Prophet (peace and blessings be upon him) said: "Whatever befalls the believer that he dislikes is a calamity."
Imam al-Tabarani recorded it with a da'if (weak) chain.

Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "When the sandal strap of any of you breaks, he should recite 'Inna lillahi wa inna ilayhi raji'un', for this too is a calamity."
Imam al-Bazzar recorded it. Its chain contains a narrator, Bakr bin Khunays, and he is da'if (weak).

Sayyiduna Shaddad bin Aws (may Allah be pleased with him) has narrated something similar from the Prophet (peace and blessings be upon him).
(Allamah al-Haythami says:) I say:
Imam al-Bazzar recorded it after the hadith of Sayyiduna Abu Hurayrah (may Allah be pleased with him). The chain of the report of Sayyiduna Shaddad (may Allah be pleased with him) contains a narrator, Kharijah bin Mus'ab, and he is matruk (abandoned).