[The superiority of combining the two prayers for the traveler]

Answer—and Allah is the granter of success: What is transmitted from the Prophet (may Allah bless him and family and grant them peace) regarding travel is combination (jamʿ) in travel. The best guidance is the guidance of Muhammad (may Allah bless him and family and grant them peace), and the Exalted has said: “Indeed, in the Messenger of Allah you have an excellent example for whoever hopes for Allah and the Last Day …” [al-Aḥzāb:21].
And in the report: “Allah loves that His concessions (rukhaṣ) be taken just as He loves that His resolutions (ʿazāʾim) be observed.” And in the ḥadīth: “Pray as you have seen me pray.”
This is what can be adduced to show that combining in travel is preferable to praying each at its set time.
Someone might say: combining in travel is a concession, whereas praying at the set times is a resolution—and a resolution is superior to a concession.
We reply: It is not far-fetched that the concession here be superior due to certain factors: the Prophet’s continuous practice, attaining emulation of him in the prayer of the traveler, and his saying: “Pray as you have seen me pray.”
There is another factor supporting what we have said: what is related from the Prophet (may Allah bless him and family and grant them peace) that “Prayer is the best theme,” and “The best of your deeds is prayer.” We saw him combine the prayers on the Day of ʿArafah and on the Night of Muzdalifah—among the greatest nights and days and noblest places. His choosing to combine in those situations indicates that combining is superior in travel.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1