Abu Khalid al-Ahmar narrated from Humayd, who said: I set out while fasting, and they said to me: "Repeat it (make it up)." I said: Sayyiduna Anas (may Allah be pleased with him) informed me that the Companions of the Prophet (peace and blessings be upon him) used to travel, and no fasting person found fault with one who was not fasting, nor one who was not fasting with a fasting person. Then I met Ibn Abi Mulaykah, and he narrated to me the like of it from Sayyidah Aishah (may Allah be pleased with her).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8163