(8) The Book on Fasting
كتاب الصوم عن رسول الله صلى الله عليه وسلم
(76) Chapter: What Has Been Related About The One Who Ate And Then Went Out To Travel
(76) باب مَا جَاءَ فِيمَنْ أَكَلَ ثُمَّ خَرَجَ يُرِيدُ سَفَرًا
Jami` at-Tirmidhi 799 
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."
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 ‏.‏
Grade :  Sahih (Darussalam)
Reference : Jami` at-Tirmidhi 799
In-book reference : Book 8, Hadith 118
English translation : Vol. 2, Book 3, Hadith 799