It is narrated from Ibn al-Musayyib (may Allah have mercy on him) that he stated: The Messenger of Allah (ﷺ) said: "The best among you are those who, when they travel, shorten the prayer and break the fast," or he said: "those who do not fast."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 355
Hadith Takhrijإسناده ضعيف لإرساله: وشيخ الشافعي متروك. أخرجه البيهقي في معرفة السنن والآثار: 1514 - وعبد الرزاق: 4480.