Musannaf Ibn Abi Shayba 3:218

Abu Bakr narrated to us, he said: Abu Usama narrated to us, from Sa’id ibn Abi ‘Aruba, from Qatada, from Yunus ibn Jubayr, from Hattan ibn ‘Abd Allah, from Abu Musa, from the Prophet (may Allah bless him and grant him peace), who said: "When the Imam says, 'Sami’a Allahu liman hamidah' (Allah hears those who praise Him), then say, 'Allahumma Rabbana laka al-hamd' (O Allah, our Lord, to You is the praise), and Allah will hear you."