The Greater Holy Assembly (Idra Rabba Qadisha) 21
443Rabbi Yehuda arose, and commenced, and said, Isa. ii. 19: “‘And they shall enter into the holes of the rocks, and into the caves of the earth, from the countenance of the terror of the Lord of Hosts, and from the glory of His majesty, when He shall arise to shake terribly the earth.’
444“‘From the countenance of the Terror of the Lord.’ It is to be carefully noted that that which is exterior is called the Terror of Tetragrammaton.
445“‘And from the Glory of His Majesty.’ These are the hairs beneath the beard, and they are called the Glory of His Majesty.