قال الله تعالى: يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِذَا لَقِيتُمْ فِئَةًۭ فَٱثْبُتُوا۟ وَٱذْكُرُوا۟ ٱللَّهَ كَثِيرًۭا لَّعَلَّكُمْ تُفْلِحُونَ

Allah SWT says: "O you who believe! When you meet (an enemy) force, take a firm stand against them and remember the Name of Allah much (both with tongue and mind), so that you may be successful.” (Quran 8:45)

This verse mentions remembering Allah in the context of fighting so this is evidence that remembering Allah gives victory and strength. It’s not just spiritual strength but physical strength as well. Another evidence for this:

عَنْ عَلِي أَنَّ فَاطِمَةَ اشْتَكَتْ مَا تَلْقَى مِنْ الرَّحَى فِي يَدِهَا وسألت عن خادم فَقَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَلَا أُعَلِّمُكُمَا خَيْرًا مِمَّا سَأَلْتُمَا

إِذَا أَخَذْتُمَا مَضَاجِعَكُمَا أَنْ تُكَبِّرَا اللَّهَ أَرْبَعًا وَثَلَاثِينَ وَتُسَبِّحَاهُ ثَلَاثًا وَثَلَاثِينَ وَتَحْمَدَاهُ ثَلَاثًا وَثَلَاثِينَ فَهْوَ خَيْرٌ لَكُمَا مِنْ خَادِمٍ

Ali reported: Fatimah complained about blisters on her hands from working the millstone and she asked for a servant. The Prophet ﷺ said, “Shall I not tell you what is better than what you ask for?

When both of you lay down to sleep, say ‘Allahu Abkar’ thirty-four times, say ‘SubhanaAllah’ thirty-three times, and say ‘Alhamdulliah’ thirty-three times. This is better for you both than a servant.” (Muslim 2727)

In this hadith, Fatimah (may Allah be pleased with her) requested physical help and the Prophet ﷺ advised her with dhikr. Ibn Al-Qayyim also mentioned,

قال ابن القيم رحمه الله: " حَضَرتُ شيخَ الإسلام (ابنِ تيمية) مرَّةً، صلَّى الفَجرَ، ثم جلَسَ يذكُرُ اللهَ تعالى إلى قريبٍ مِنَ انتِصافِ النهارِ، ثم التَفتَ إليَّ، وقال: هذه غَدْوتي، ولو لم أتغَدَّ الغَداءَ، سقَطَتْ قُوَّتي " . (كتاب الوابل الصيب, ص: 42)

Ibn al-Qayyim, may Allah have mercy on him, said: “I attended the Sheikh of Islam (Ibn Taymiyya) once. He prayed fajr, then sat remembering Allah SWT until close to midday. Then he turned to me and said: ‘This is my morning meal, and if I did not eat it, my strength would fail.’”

(al-Wabil al-Sayyib, Pg. 42)

وقال ابن القيم رحمه الله: أن الذكر يعطي الذاكر قوة، حتى إنه ليفعل مع الذكر ما لم يظن فعله بدونه، وقد شاهدت من قوة شيخ الإسلام ابن تيمية في سننه وكلامه وإقدامه وكتابه أمراً عجيباً، فكان يكتب في اليوم من التصنيف ما يكتبه الناسخ في جمعه وأكثر، وقد شاهد العسكر من قوته في

الحرب أمراً عظيماً (كتاب الوابل الصيب, ص: 77)

Ibn al-Qayyim, may Allah have mercy on him, said: “Dhikr gives a person strength so that he can do with dhikr that which he cannot do without it. I saw wonders in the strength of Shaykh al-Islam Ibn Taymiyah in walking, speech, courage and writing. He used to write in one day

what a scribe would write in a week, or more. The troops saw his amazing strength in war.” (al-Wabil al-Sayyib, Pg. 77)

وقال ابن رجب رحمه الله: الذكر قوت قلوب العارفين يغنيهم عن الطعام والشراب كما قيل: أنت ربي إذا ظمئت إلى الماء ... وقوتي إذا أردت الطعاما لما جاع المجتهدون شبعوا من طعام المناجاة فأف لمن باع لذة المناجاة بفضل لقمة. (ص188 - كتاب لطائف المعارف)

Ibn Rajab, may Allah have mercy on him, said: “The remembrance of Allah is the food of the 'arifun (those who truly recognized Allah). It makes them independent of food and drink. As a poet says:

"You are my thirst-quencher when I am thirsty for water, and you are my strength when I need food."

When those who are engaged in tahajjud salah become hungry, they fill themselves with the food of private conversation with Allah. Destruction to the person who sells the joy of private conversation with Allah for a morsel of food.” (Lataaif al-Ma'aarif, p.188)

There are also some hadiths which mention that dhikr will replace food for the believers during the fitnah of the Dajjal:

قال رسول الله صلى الله عليه وسلم: وإنَّ قبلَ خروجِ الدَّجَّالِ ثلاثَ سنواتٍ شِدادٍ ، يُصِيبُ الناسَ فيها جُوعٌ شديدٌ ، يأمرُ اللهُ السماءَ السنةَ الأولى أن تَحْبِسَ ثُلُثَ مَطَرِها ، ويأمرُ الأرضَ أن تَحْبِسَ ثُلُثَ نباتِها ،

ثم يأمرُ السماءَ في السنةِ الثانيةِ فتَحْبِسُ ثُلُثَيْ مَطَرِها ، ويأمرُ الأرضُ فتَحْبِسُ ثُلُثَيْ نباتِها ، ثم يأمرُ السماءَ في السنةِ الثالثةِ فتَحْبِسُ مطرَها كلَّه ، فلا تَقْطُرُ قُطْرةً ، ويأمرُ الأرضَ فتَحْبِسُ نباتَها كلَّه فلا تُنْبِتُ خضراءَ ،

فلا يَبْقَى ذاتُ ظِلْفٍ إلا هَلَكَت إلا ما شاء اللهُ ، قيل : فما يُعِيشُ الناسَ في ذلك الزمانِ ؟ قال : التهليلُ ، والتكبيرُ ، والتحميدُ ، ويُجْزِئُ ذلك عليهم مَجْزَأَةَ الطعامِ. (وصححه الألباني في صحيح الجامع، 7875)

The Messenger of Allah (ﷺ) said: “Before Dajjal appears there will be three difficult years in which the people will suffer severe famine. In the first year, Allah will command the sky to withhold one third of its rain and the earth to withhold one third of its produce.

In the second year, He will command the sky to withhold two thirds of its rain and the earth to withhold two-thirds of its produce. In the third year, he will command the sky to withhold all of its rain, and not a single drop will fall,

and the earth to withhold all of its produce, and nothing will grow. All cloven-hoofed animals will die, except those that Allah wills.' It was said: 'What will the people live on at that time?' He said: Tahleel (saying La ilaha illallah), Takbir (saying Allahu Akbar),

and Tamheed (saying Alhamdulliah). That will take the place of food for them.'" (Al-Albani authenticated it in Sahih al-Jami, 7875)

أَنَّ رَسُولَ اللهِ ﷺ ذَكَرَ جَهْدًا يَكُونُ بَيْنَ يَدَيِ الدَّجَّالِ فَقَالُوا أَيُّ الْمَالِ خَيْرٌ يَوْمَئِذٍ؟ قَالَ غُلَامٌ شَدِيدٌ يَسْقِي أَهْلَهُ الْمَاءَ وَأَمَّا الطَّعَامُ فَلَيْسَ قَالُوا فَمَا طَعَامُ الْمُؤْمِنِينَ يَوْمَئِذٍ؟ قَالَ التَّسْبِيحُ وَالتَّكْبِيرُ

وَالتَّحْمِيدُ وَالتَّهْلِيلُ قَالَتْ عَائِشَةُ فَأَيْنَ الْعَرَبُ يَوْمَئِذٍ؟ قَالَ الْعَرَبُ يَوْمَئِذٍ قَلِيلٌ (أحمد:٢٤٤٧٠)

The Messenger of Allah (ﷺ) mentioned a struggle that will take place during the time of the Dajjal (false messiah). They asked, "Which wealth is the best at that time?" He (ﷺ) said, "A strong youth who serves his family with water. As for food, there will be no more.”