Musannaf Ibn Abi Shayba 27:713

Ali bin Hashim narrated to us, from Ibn Abi Layla, from Muhammad bin Abd al-Rahman, from Ibn Sharhabil, from Qays bin Sa'd bin Ubada, from the Prophet, may Allah bless him and grant him peace, that he said: "O Allah, send blessings upon the Ansar, and upon the descendants of the Ansar, and upon the descendants of the descendants of the Ansar."