Musnad Abu Ya'la al-Mawsili 150:450

Ahmad ibn Mani' narrated to us, Marwan narrated to us, from Razin al-Bakri, a freedwoman of ours called Salma from Bakr ibn Wa'il narrated to us that she heard Aisha saying: The Messenger of Allah (peace be upon him) entered and said: "O Aisha, is there any morsel?" I brought him a loaf of bread, and he placed it to his mouth and said: "O Aisha, has anything of it entered my stomach?" Likewise is the kiss of the fasting person; breaking the fast is only from what enters, not from what exits.