Ibn Taymiyyah wrote, “Remembrance of Allah is to the heart what water is to fish. What happens to a fish when it is taken out of water?”
Muhammad Salih Al-Munajjid on dhikr:
“This is one of the greatest means of being steadfast in Islam.
Think about the combination descried in this Ayah:
يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓاْ إِذَا لَقِيتُمۡ فِئَةً۬ فَٱثۡبُتُواْ وَٱذۡڪُرُواْ ٱللَّهَ ڪَثِيرً۬ا لَّعَلَّكُمۡ تُفۡلِحُونَ
“O you who believe! When you meet (an enemy) force, take a firm stand against them and remember the Name of Allâh much (both with tongue and mind), so that you may be successful”
[Surah Al-Anfal (8):45]
Dhikr is one of the most effective aids to standing firm in jihad.
“Think about how the physical strength of the Persians and Romans let them down when they needed it most” Ibn Al Qayyim, may Allah swt have Mercy on him, in Ad Da’wa As Dwa said: despite the small numbers of men and weapons of those who remembered the Name of Allah swt much, won.
How did Yusuf (as) stand firm in the face of temptation of the part of the powerful and beautiful woman who called him to do wrong? Did he not enter the fortress of “seeking refuge in Allah swt” and thus defeated the waves of temptation? This is the effect of adhkar [remembering Allah swt] on making the believers steadfast.
[Means of steadfastness in Allah’s Religion, page 18]