حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ جَعْفَرٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنْ مُحَمَّدِ بْنِ الْمُنْكَدِرِ، عَنْ مُحَمَّدِ بْنِ كَعْبٍ، أَنَّهُ قَالَ أَتَيْتُ أَنَسَ بْنَ مَالِكٍ فِي رَمَضَانَ وَهُوَ يُرِيدُ سَفَرًا وَقَدْ رُحِلَتْ لَهُ رَاحِلَتُهُ وَلَبِسَ ثِيَابَ السَّفَرِ فَدَعَا بِطَعَامٍ فَأَكَلَ فَقُلْتُ لَهُ سُنَّةٌ قَالَ سُنَّةٌ ‏.‏ ثُمَّ رَكِبَ ‏.‏

Muhammad bin Ka’b narrated:
“I went to Anas bin Malik during Ramadan and he was about to travel. His mount was prepared for him, and he put on his traveling clothes, then he called for some food to eat, and I said to him: ‘Is it Sunnah?’ He said: ‘It is Sunnah.’ Then he rode.”
Ash-Shaykh Albany rahimahullah wrote a booklet [pdf of booklet] on the aforementioned narration clarifying that if a person has prepared himself for his journey and made his intention to travel on that day, then he could break his fast after dawn before departing his city. And Allaah knows best.
Mentioned by

AbdulFattaah Bin Uthman
Abu Fajr