From Sahih Muslim (Hadith 2620):
Humaid reported that Anas (Allah be pleased with him) was asked about fasting during Ramadan while travelling. He said:We travelled with the Messenger of Allah (ﷺ) during the month of Ramadan, but neither the observer of the fast found fault with the breaker of the fast, nor the breaker of the fast found fault with the observer of the fast
Reference: Muslim 2620