Musnad Ahmad 1153:1657

Yahya ibn Sa'id narrated to us, from Isma'il, who said: 'Amir narrated to us, from Abu Bakr ibn 'Abd al-Rahman, that he came to 'Aisha and said: "Abu Hurayrah gives us a fatwa that whoever wakes up in a state of janabah (major ritual impurity), there is no fasting for him. So what do you say about that?" She said: "I do not say anything about that. The caller used to call for prayer, and I would see the water dripping between his shoulder blades, then he would pray the dawn prayer, then he would remain fasting."