Musannaf Ibn Abi Shayba 35:242

Ibn ‘Ulayyah narrated to us, from Sa‘id, from Qatadah, from ‘Urwah, from Sa‘id ibn ‘Abd al-Rahman ibn Abza, from his father, from ‘Ammar, from the Prophet (may Allah bless him and grant him peace), who said: "Tayammum is one strike for the face and the palms."