Musannaf Ibn Abi Shayba 3:1436

Ubayd Allah narrated to us, he said: Shayban informed us, from Yahya, from Muhammad ibn Ibrahim, that Khalid ibn Ma'dan narrated to him, that Jubayr ibn Nufayr narrated to him, that al-Irbad ibn Sariyah narrated to him—and al-Irbad was among the People of the Suffah—he said: The Prophet, may Allah bless him and grant him peace, used to pray for the first row three times, and for the second row once.