Sahih Al Bukhari Hadith Number 1947

Narrated Anas bin Malik: We used to travel with the Prophet (peace be upon him) and neither did the fasting persons criticize those who were not fasting, nor did those who were not fasting criticize the fasting ones.

30  Fasting
Hadith number 1947
Volume no 3
Chapter: 37 (Not to criticize each other for observing Saum or not (on journeys)