Musnad Ahmad 28:263

Musa ibn Dawud narrated to us, Ibn Lahi'ah narrated to us, from Yazid ibn Abi Habib, from Qaysar al-Tujibi, from Abdullah ibn Amr ibn al-As, who said: We were with the Prophet, peace and blessings of Allah be upon him, when a young man came and said: "O Messenger of Allah, may I kiss [my wife] while I am fasting?" He said: "No." Then an old man came and said: "May I kiss [my wife] while I am fasting?" He said: "Yes." He said: So we looked at one another. The Messenger of Allah, peace and blessings of Allah be upon him, said: "I know why you looked at one another; the old man controls himself."