John Gill Commentary Ruth 3:17

"And she said, These six [measures] of barley gave he me; for he said, Go not empty unto thy mother-in-law." — Ruth 3:17 (ASV)

And she said, these six measures of barley gave he me
Which she laid down before her, which was a proof of his kindness to her, that she was acceptable to him, and had well sped; of these six measures, see (Ruth 3:15) which by some are allegorically interpreted of six blessings that should be bestowed upon her, as the spirit of wisdom, understanding as (Isaiah 11:2) so Jarchi; or of six persons that should spring from her, as David, Daniel, and his companions, and the King Messiah, as the Targum:

for he said unto me, go not empty unto your mother in law ;
which, as it expressed a regard to Naomi, and a compassionate concern for her support, so would give her assurance of the success Ruth met with, she would relate to her.