Albert Barnes Commentary Ruth 2:14

"And at meal-time Boaz said unto her, Come hither, and eat of the bread, and dip thy morsel in the vinegar. And she sat beside the reapers, and they reached her parched grain, and she did eat, and was sufficed, and left thereof." — Ruth 2:14 (ASV)

To dip the morsel, or sop, whether it was bread or meat, in the dish containing the vinegar (Mark 14:20; Numbers 7:13) was, and still is, the common custom in the East.

Parched or “roasted” corn - Grain was the common food of the country then (Compare to 1 Samuel 17:17; 1 Samuel 25:18; 2 Samuel 17:28) as it is now.

And left - Or “reserved” (Ruth 2:18). Rather, “had some over” . Ruth 2:18 tells us that she took to her mother-in-law what she had left over.