Praise be to Allah.
We have previously stated in the answer to question no. 20165 that if the traveller is finding it too difficult to fast, then it is better for him to break his fast, and fasting is makrooh for him. His fasting may become haraam if it leads to harm or the fear that he may die.
The hadeeth to which the questioner refers may be interpreted in this way, i.e., if the traveller finds it extremely difficult to fast or if he will be harmed by fasting. The context of the hadeeth indicates this.
Muslim (1114) narrated from Jaabir ibn ‘Abd-Allaah (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) set out for Makkah in the year of the Conquest in Ramadaan, and he fasted until he reached Kuraa’ al-Ghameem – which is a place between Makkah and Madeenah. It was said to him that the people were finding it hard to fast, and they were waiting to see what he would do. He called for a vessel of water after ‘Asr, and he lifted it up so that the people could see it, then he drank from it. It was said to him afterwards that some of the people were still fasting. He said, “Those people are disobedient, those people are disobedient.”
From the context of the hadeeth it may be understood that the Prophet (peace and blessings of Allaah be upon him) called them disobedient for two reasons:
1 – They continued to fast even though it was difficult for them
2 – The Prophet (peace and blessings of Allaah be upon him) broke his fast so that they would follow his example, so it was as if he had commanded them to break their fast but they did not do so, so he called them disobedient.
This hadeeth is to be understood as referring to cases when fasting is harmful… This interpretation is supported by the fact that the hadeeth says that the people were finding it hard to fast. Based on this, fasting whilst travelling is not regarded as an act of disobedience or sin if a person is not harmed by it.
Ibn al-Qayyim said in Tahdheeb al-Sunan:
With regard to the words of the Prophet (peace and blessings of Allaah be upon him), “Those people are disobedient,” that applies to one specific case, when he wanted them to break their fast and some of them went against him, so he said that… The Prophet (peace and blessings of Allaah be upon him) broke his fast after ‘Asr so that his example would be followed, and when some of them did not follow his example, he said, “Those people are disobedient,” but he did not mean by that that it is haraam for the traveller to fast in all cases.
The Prophet (peace and blessings of Allaah be upon him) called those people who continued to fast whilst travelling disobedient because he had told them to do something and they went against that.
Based on this, the hadeeth applies to a specific situation, and it is not right to apply it to all those who fast whilst travelling.
That is also indicated by the fact that it is proven that the Prophet (peace and blessings of Allaah be upon him) used to fast whilst travelling. If it was a sin to do so then the Prophet (peace and blessings of Allaah be upon him) would not have done that.
And Allaah knows best.