John Lightfoot on Luke 24:15

[Jesus himself drew near, and went along with them.] "After that, he appeared in another form unto two of them, as they walked, and went into the country." But what form that was, it would be something bold to determine. But it seems to be different from the form of a gardener, and indeed not the form of any plebeian; but rather of some scholar, because he instructs them while they were upon the road, and giveth thanks for them when they sat at meat. So Beracoth; "If two eat together, the one of them a learned man, the other of them an unlearned man, he that is the learned man gives thanks." Hence that passage: "Janneus the king calls out Simeon Ben Shetahh, vice-president of the Sanhedrim, and a doctor, to say grace after supper: and thus he begins; 'Blessed be God for the meat which Janneus and his guests have eaten.' To whom the king, 'How long wilt thou persist in thy frowardness?' Saith the other, 'Why, what should I have said? Must we bless God for the meat that we have eaten, when as I have eaten none at all?'"