The concession to break the fast while travelling, and the validity of the fast of one who fasts during it

It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both): "The Messenger of Allah (peace and blessings be upon him) travelled in the month of Ramadan, and he (peace and blessings be upon him) (sometimes) fasted (during the journey) and (sometimes) broke the fast."
Imam Abu Ya'la (may Allah have mercy on him) says: Khalaf bin Hisham also narrated this hadith to us, from Abu al-Ahwas, from Muslim Abu Abdullah, through Imam Mujahid, with the same meaning.

It is narrated from Abu Sa'id, the freed slave of al-Mahri (may Allah have mercy on him), that he said: I was returning from Umrah with a companion of mine when we saw the crescent of Ramadan. Then, on an extremely hot day, we camped on the land of Sayyiduna Abu Hurayrah (may Allah be pleased with him). That day all of us except one man had not fasted (because of the journey). At midday Sayyiduna Abu Hurayrah (may Allah be pleased with him) came to us and saw that our companion (unable to bear the heat) was seeking the coolness of the date palms. He (may Allah be pleased with him) asked: "What is the matter with this companion of yours?" The people said: He is fasting. He (may Allah be pleased with him) said: "What compelled him not to break his fast, when Allah Almighty has granted him the concession (to break the fast on a journey)? If he had died (in this state), I would not even have offered his funeral prayer."
This report is mawquf and sahih (authentic).

It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with him) that he said: "Not fasting and breaking the fast during a journey is a firm decision and an emphatic command from Allah Almighty."
This report is mawquf, and its chain is sahih (authentic).

It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) used to (sometimes) fast during a journey and (sometimes) break the fast (that is, at times he would fast and at times he would leave it).

It is narrated from Ghitrif Abu Harun that the Messenger of Allah (peace and blessings be upon him) sent two men on an errand in the month of Ramadan. He (peace and blessings be upon him) had instructed one of them in advance (in view of the hardship of the journey) not to fast, while he remained silent regarding the other, so he fasted. When the two of them returned to his presence, he asked: "What did the two of you do?" One of them said: I fasted, and the other said: I did not fast. So he (peace and blessings be upon him) said: "Both of you have done right."
This report, despite being mursal, has a hasan (good) chain.

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.

It is narrated from Sa'id bin Jubayr (may Allah have mercy on him) that the Commander of the Believers, Sayyiduna Umar bin al-Khattab (may Allah be pleased with him), came to an army that was besieging a fortress, and he (may Allah be pleased with him) ordered them (in order to preserve their strength and vigour in the campaign) to break their fast.

It is narrated from Ubayd bin Umayr that the Messenger of Allah (peace and blessings be upon him) said on the day of the Conquest of Makkah: "All of you break (your fast), for this is a day of fighting and battle with the enemy."

It is narrated from Nafi' (may Allah have mercy on him) that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both), in the month of Ramadan, set out hastily from Madinah towards Makkah out of fear (and to avoid) a fitnah breaking out there. He broke his fast (in view of the legal concession during travel). Then, on the night on which he was to enter Makkah, he began the following morning fasting, that is, he was fasting.