It is narrated from Anas (may Allah be pleased with him) who states: We traveled with the Messenger of Allah (peace be upon him). Some of us were fasting and some were not. So the one who was fasting did not find fault with the one who was not fasting, and the one who was not fasting did not find fault with the one who was fasting.
Hadith Referenceمسند الإمام الشافعي / كتاب الصيام / 627
Hadith Takhrijصحيح اخرجه البيهقى فى المعرفة السنن والآثار (2519) ۔ وانظر الحديث الذي قبله برقم (626)۔