فأمر تعالى بالثبات عند قتال الأعداء والصبر على مبارزتهم فلا يفروا ولا ينكلوا ولا يجبنوا وأن يذكروا الله في تلك الحال ولا ينسوه بل يستعينوا به ويتوكلوا عليه ويسألوه النصر على أعدائهم وأن يطيعوا الله ورسوله في حالهم ذلك فما أمرهم الله تعالى به ائتمروا وما نهاهم عنه انزجروا ولا يتنازعوا فيما بينهم أيضاً فيختلفوا فيكون سبباً لتخاذلهم وفشلهم ﴿ وتذهب ريحكم ﴾ أي قوتكم وحدتكم وما كنتم فيه من الإقبال ﴿ واصبروا إن الله مع الصابرين ﴾ وقد كان للصحابة رضي الله عنهم في باب الشجاعة والائتمار بما أمرهم الله ورسوله به وإمتثال ما أرشدهم إليه ما لم يكن لأحد من الأمم والقرون قبلهم ولا يكون لأحد ممن بعدهم فإنهم ببركة الرسول ﷺ وطاعته فيما أمرهم فتحوا القلوب والأقاليم شرقاً وغرباً في المدة اليسيرة مع قلة عددهم بالنسبة إلى جيوش سائر الاقاليم من الروم والفرس والترك والصقالبة والبربر والحبوش وأصناف السودان والقبط وطوائف بني آدم قهروا الجميع حتى علت كلمة الله وظهر دينه على سائر الأديان وامتدت الممالك الاسلامية في مشارق الأرض ومغاربها في أقل من ثلاثين سنة فرضي الله عنهم وأرضاهم أجمعين وحشرنا في زمرتهم إنه كريم وهاب
تفسير إبن كثير الانفال ٤٥-٤٦
The Most High ordered perseverance when fighting enemies and steadfastness in combating them. People are not to flee, not shy away, and not grow cowardly; they are to make remembrance of Allah under these circumstances and not forget Him, but rather invoke His aid, trust in Him, and ask Him for victory over their enemies; they are to obey Allah and His Messenger when they are in this situation, deliberating on what Allah Most High has ordered them, and guarding restraint against what He has forbidden them. Nor are they to quarrel with each other, or differ, such that this leads to their frailty and failure; { such that you lose heart } : that is, your strength and vitality, and the enthusiasm you feel. { And be steadfast; indeed Allah is with those who are steadfast } : the Companions (may Allah be pleased with them) – in their courage and deliberation in what Allah and His Messenger ordered, and observance of what He guided them towards – had what no other nation or generation before them had, or any after them will have. Indeed, by the blessing of the Messenger (SAW) and obedience to him in what Allah had ordered them, they opened hearts as well as territories east and west in a brief span of time, in spite of their small number compared to the armies of the other territories – the Romans, Persia, the Turks, the Slavs, the Berbers, the Ethiopians, the different classes in Sudan, the Copts, and all factions of mankind; they conquered all of them, until the word of Allah rose high and His religion [deen] was manifest above all other religions. The Islamic empires spread out to the eastern and western regions of the earth in less than thirty years. So then may Allah be pleased with them and give pleasure to them all, and gather us up among their league; indeed He is generous, granting.
Tafsir Ibn Kathir, Al-anfal 45-46