John Gill Commentary Mark 14:19

"They began to be sorrowful, and to say unto him one by one, Is it I?" — Mark 14:19 (ASV)

And they began to be sorrowful
And were so, all but Judas, at this saying of Christ's:

and to say unto him, one by one ;
even till it came to Judas himself,

is it I ?
that shall betray you;

and another said, is it I ?
This clause is wanting in the Vulgate Latin, Syriac, Arabic, Persic, and Ethiopic versions, and in two of Beza's copies; and indeed seems to be redundant, since the disciples are said before to express themselves in this manner, one by one; (See Gill on Matthew 26:22).