It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him); he said: We besieged Tustar (a city in Iran), and at that time Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) was our commander. He fasted, and we also fasted along with him.
Explanation: According to the scholars of hadith, this report establishes the permissibility of fasting during travel and a long siege in jihad, provided that it does not cause physical weakness in facing the enemy.
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب الصيام / 1042
Hadith Gradingمحدثین:إسناده ضعيف
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :إسناده ضعيف. » «أخرجه مصنف ابن أبي شيبة برقم: 9070»