Or because Luke has twice mentioned the cup, first before Christ gave the bread, then after He had given it, on the first occasion he has anticipated, as he frequently does, but on the second that which he has placed in its natural order, he had made no mention of before. But both joined together make the same sense which we find in the others, that is, Matthew and Mark.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: de Con. Ev. lib. iii. c. 1.