Sahih Muslim Book 6, Hadith Number 2442.

Chapter : Kissing is not forbidden while fasting if one is not urged by sexual lust.

Aswad reported: I and Masruq went to ‘Aisha (Allah be pleased with her) and asked her if the Messenger of Allah (may peace be upon him) embraced (his wives) while fasting. She said: Yes; but he had the greatest control over his desire among you: or he was one of those who had control over his desire. It is further narrated on the authority of Aswad and Masruq that they went to the Mother of the Believers and they asked her (and the rest of the Hadith is the same)