It was the practice of the Prophet (peace and blessings be upon him):
"When he (peace and blessings be upon him) stopped at a halting place, he would not move on without praying the Zuhr prayer."
Hadith Referenceصحیح الجامع الصغیر / حرف الكاف / 4793
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[حم د ن] عن أنس. صحيح أبي داود ١٠٨٨.