It is narrated from Hazrat Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) used to combine the Zuhr and Asr prayers, and the Maghrib and Isha prayers while on a journey.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 12408
Hadith Gradingحکم دارالسلام:إسناده صحيح، خ: 1108 معلقا، و 1110 موصولا