Adam Clarke on Isaiah 6:1

The Lord - Fifty-one MSS. of Kennicott's, and fifty-four of De Rossi's, and one edition; in the 8th verse, (Isa 6:8); forty-four MSS. of Kennicott's, and forty-six of De Rossi's, and one edition; and in the 11th verse (Isa 6:11); thirty-three MSS. of Kennicott's, and many of De Rossi's, and one edition, for אדני Adonai, "the Lord" read יהוה "Jehovah," which is probably the true reading; (compare Isa 6:6); as in many other places, in which the superstition of the Jews has substituted אדני Adonai for יהוה Yehovah. One of my own MSS., a very ancient and large folio, to which the points and the masora have been added by a later hand, has יהוה Yehovah in the 1st and 8th verses, in the teeth of the masora, which orders it in both places to be read אדני Adonai.