Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
suyuti:1221a –

“If you are called to arms then go forth.” (Using translation from Ibn Mājah 2773)   

السيوطي:١٢٢١a –

"إِذَا استُنْفِرتُمْ فَانْفِرُوا".  

[هـ] ابن ماجة عن ابن عباس

See similar narrations below:

Collected by Ibn Mājah
ibnmajah:2773 – Aḥmad b. ʿAbd al-Raḥman b. Bakkār b. ʿAbd al-Malik b. al-Walīd b. Busr b. Abū Arṭāh > al-Walīd > Shaybān > al-Aʿmash > Abū Ṣāliḥ > Ibn ʿAbbās

“If you are called to arms then go forth.”  

ابن ماجة:٢٧٧٣ – حَدَّثَنَا أَحْمَدُ بْنُ عَبْدِ الرَّحْمَنِ بْنِ بَكَّارِ بْنِ عَبْدِ الْمَلِكِ بْنِ الْوَلِيدِ بْنِ بُسْرِ بْنِ أَبِي أَرْطَاةَ حَدَّثَنَا الْوَلِيدُ حَدَّثَنِي شَيْبَانُ عَنِ الأَعْمَشِ عَنْ أَبِي صَالِحٍ عَنِ ابْنِ عَبَّاسٍ

عَنِ النَّبِيِّ ﷺ قَالَ إِذَا اسْتُنْفِرْتُمْ فَانْفِرُوا