Musannaf Ibn Abi Shayba 2:243

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from ‘Asim ibn ‘Ubayd Allah, from ‘Ubayd Allah ibn ‘Abd Allah ibn al-Harith, from his father, that the Prophet, may Allah bless him and grant him peace, used to say the same as what the caller to prayer (mu’adhdhin) says. When he reached "Hayya ‘ala al-salah" (come to prayer) and "Hayya ‘ala al-falah" (come to success), he would say: "La hawla wa la quwwata illa billah" (there is no power and no strength except by Allah).