Musnad Ahmad 1153:1045

Waki’ narrated to us, Hammad bin Salamah narrated to us, from Khalid al-Hadhdha’, from Khalid bin Abi as-Salt, from ‘Arak, from ‘Aisha, she said: The Messenger of Allah, may Allah bless him and grant him peace, said: "They have done it; they have faced my posterior toward the Qibla."