A.T. Robertson Commentary Matthew 5:6

"Blessed are they that hunger and thirst after righteousness: for they shall be filled." — Matthew 5:6 (ASV)

They that hunger and thirst after righteousness (ο πεινωντες κα διψωντες την δικαιοσυνην). Here Jesus turns one of the elemental human instincts to spiritual use. There is in all men hunger for food, for love, for God. It is passionate hunger and thirst for goodness, for holiness. The word for "filled" (χορτασθησοντα) means to feed or to fatten cattle from the word for fodder or grass like Mr 6:39 "green grass" (χορτος χλωρος).