Dhikr at Times of Tribulation and Hardship
Question

Are there any Du`a’s that we can say at times of calamity and tribulation such as war and the disbelievers' attacks against Muslim countries?
Praise be to Allah.The Prophet’s prayers at times of tribulation
The Prophet (peace and blessings of Allah be upon him) used to seek refuge with Allah a great deal from trials and tribulations , as it says in the Hadith of Zayd ibn Thabit (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) said, “Seek refuge with Allah from trials and tribulations, both visible and hidden.” (Narrated by Muslim, 2867) 
It was narrated from Ibn `Abbas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: “My Lord came to me tonight in the most beautiful form…” and in this Hadith he said that Allah said, “O Muhammad, when you pray, then say: `Allahumma inni as’aluka fi`l Al-khayrat wa tark Al-munkarat, wa hubb Al-masakin, wa an taghfira li wa tarhamani wa tatuba `alayya. Wa in aradta bi `ibadika fitnatan, faqbidni ilayka ghayra maftun (O Allah, I ask You (to enable me) to do good deeds and avoid evil deeds, and to love the poor, and (I ask You) to forgive me, have mercy on me and accept my repentance. If You will that some trial should befall Your slaves, then take me to You [i.e., cause me to die] without having subjected to that trial).” (Narrated by At-Tirmidhi, 3233; Al-Albani said of this Hadith is authentic in Sahih At-Targhib wat-Tarhib, 408) 
The Prophet (peace and blessings of Allah be upon him) used to seek refuge from trials and tribulations because when they come they do not befall the wrongdoers only, rather they befall everyone. 
Du`a at times of tribulation and hardship
It is a good idea to acquaint ourselves with the Hadiths that mention Dhikrs which have to do with trials and tribulations and disasters, so that we may call upon Allah with these words and spread this knowledge and memorize whatever we can of them… and understand their meanings so that we can worship Allah by means of them, because they are the greatest words that can be spoken in these circumstances. 
·         Abu Burdah ibn `Abdullah narrated from his father that when the Prophet (peace and blessings of Allah be upon him) was afraid of some people he would say, “Allahumma inna naj`aluka fi nuhurihim wa na`udhu bika min shururihim (O Allah, we place You before them and we seek refuge in You from their evil).” (Narrated by Abu Dawud, 1537; classed as authentic by Al-Albani in Sahih Abu Dawud, 1360)
·         It was narrated from Ibn `Abbas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) used to say at times of distress : “La ilaha ill-Allah Al-`Athim Al-Halim, la ilaha ill-Allah Rabb Al-`Arsh Al-`Athim, la ilaha ill-Allah Rabb us-samawati wa Rabb ul-ard wa Rabb ul-`Arsh il-karim (There is none worthy of worship but Allah, the All-Powerful, the Forbearing; there is none worthy of worship but Allah, Lord of the mighty Throne; there is none worthy of worship but Allah, Lord of heaven, Lord of earth, and Lord of the noble Throne).” (Narrated by Al-Bukhari, 6345; Muslim, 2730)
·         The Prophet (peace and blessings of Allah be upon him) said: “The words of relief are: La ilaha ill-Allah Al-`Athim Al-Halim, la ilaha ill-Allah Rabb Al-`Arsh Al-`Athzim, la ilaha ill-Allah Rabb us-samawati wa Rabb ul-ard wa Rabb ul-`Arsh il-karim (There is none worthy of worship but t Allah, the All-Powerful, the Forbearing; there is none worthy of worship but Allah, Lord of the mighty Throne; there is none worthy of worship but Allah, Lord of heaven, Lord of earth, and Lord of the noble Throne).” (Sahih Al-Jami` As-Saghir wa Ziyadatuhu, 4571) 
·         When the Prophet (peace and blessings of Allah be upon him) went on a military campaign he would say, `Allahumma anta `adudi wa anta nasiri wa bika uqatil (O Allah, You are my help and You are my support and by Your help I fight).” (Narrated by At-Tirmidhi, 3584; classed as authentic by Al-Albani in Sahih At-Tirmidhi, 2836.)
·         The Prophet (peace and blessings of Allah be upon him) said: “Shall I not tell you of something that, if any worldly calamity or disaster befalls any man among you and he says these words, he will be relieved of it. (It is) the Du’a’ of Dhu’n-Nun: “La ilaha illa anta subhanaka inni kuntu min Ath-thalimin (none has the right to be worshipped but You (O Allah), Glorified (and Exalted) be You [above all that (evil) they associate with You]! Truly, I have been of the wrongdoers).” According to another report: “No Muslim man says this Du’a’ concerning anything but Allah will answer his prayer.” (Sahih Al-Jami’ As-Saghir wa Ziyadatuhu, 2065)
·         The Messenger of Allah (peace and blessings of Allah be upon him) used to teach his Companions to say these words when they felt afraid: “A’udhu bi kalimat-illah il-tammati min ghadabihi wa min sharri `ibadihi wa min hamazat Ash-shayatini wa an yahdurun (I seek refuge in the perfect words of Allah from His wrath and from the evil of His slaves and from the evil promptings of the devils and from their presence).” (Narrated by Abu Dawud, 3893; classed as sound by Al-Albani in Sahih Abu Dawud, 3294)
·         The Messenger of Allah (peace and blessings of Allah be upon him) said: “The Du’a’ of the person who is in distress is: `Allahumma rahmataka arju fa la takilni ila nafsi tarfat `ayn wa aslih li sha’ni kullahu la ilaha illa anta (O Allah, for Your mercy I hope, so do not leave me in charge of my affairs even for the blink of an eye; rectify all my affairs. There is none worthy of worship but You)’” (Narrated by Abu Dawud, 5090; classed as sound by Al-Albani in Sahih Abu Dawud, 4246) 
·         If some matter was troubling him, he would say, Ya Hayyu ya Qayyum bi rahmatika astaghith (O Ever-Living, O Sustainer, by Your mercy I seek Your help).” According to another report: “If some matter worried him or distressed him.” Sahih Al-Jami` As-Saghir, 4791) 
The Messenger of Allah (peace and blessings of Allah be upon him) said: to Asma’ bint `Umays (may Allah be pleased with her), “Shall I not teach you some words which you can say at times of distress and hardship ? `Allahu Allahu rabbi la ushriku bihi shay’an (Allah is my Lord, I do not associate anything with Him).’” (Narrated by Abu Dawud, 1525; classed as authentic by Al-Albani in Sahih Abu Dawud, 1349) 
According to a version narrated in Al-Sahih Al-Jami’, “Whoever is afflicted by worry, distress, sickness or hardship, and says, Allahu Allahu rabbi la sharika lah (Allah is my Lord, He has no partner or associate), will be relieved of that.” 
And there are other Hadiths which will have a positive effect in times of tribulation and fear, bringing peace of mind and physical safety, and drawing one closer to Allah… We should be content with that which has been narrated in authentic reports from the Prophet (peace and blessings of Allah be upon him), for that is sufficient and we have no need to report that are not sound. This is better. And Allah knows best. 
For more details, please see the following answers: 12715 , 9577 , 21677 , 22438 , 20176 , 84030 , and 174515 .
And Allah knows best.