John Gill Commentary Mark 14:67

"and seeing Peter warming himself, she looked upon him, and saith, Thou also wast with the Nazarene, [even] Jesus." — Mark 14:67 (ASV)

And when she saw Peter warming himself
At the life which was in the midst of the hall:

she looked upon him ;
very earnestly, knowing him to be the same, she had let in at the motion of one, that was known in the high priest's family; and suspecting him, by being a stranger, and by his looks:

and said, and you also were with Jesus of Nazareth ;
that is, one of his disciples; (See Gill on Matthew 26:69).