Musannaf Ibn Abi Shayba 3:3697

Muhammad ibn Fudayl narrated to us, from Yahya ibn Sa’id, who said: Al-Hakam ibn Utaybah asked Al-Qasim about the blind man: "Does he lead [the prayer], and is his testimony valid?" He replied: "What prevents him from leading [the prayer], and [why would] his testimony not be valid?"