Tosefta על ברכות 4:7

A person in rags may lead the responsive reading of the Shema, and may translate [the Torah reading into Aramaic] (Meg. 4:6). Rabban Shimon ben Gamaliel says, he should be careful that he does not expose himself. A blind man may lead the responsive reading of the Shema and may translate. Rabbi Yehuda says, anyone who never saw light in all his days may not lead the responsive reading of the Shema. They said to him, many [Sages] have expounded upon the Divine Chariot (Ezek. 1) even though they never saw it. A Kohen that has a [disqualifying] blemish on his face, on his hands, or on his feet, behold, he may not lift up his hands [for the Priestly Blessing] because the people will look at him. But if there was a quorum of ten (chaver ir, see Ber. 4:7), behold, it is permitted. Behold, if he had on an otef (a type of cloak), or a smock, or a traveling cloak, he has no dignity such as to read [from the Torah]] or translate or pass before the Ark, or to lift his hands [for the Priestly Blessing].