Rashi

And lambs shall graze as their wont The righteous who are compared to a flock of ewes. as their wont Heb. כדברם. According to their habit, with equity and with a measure, guiding their affairs with justice, like these lambs. [Variant reading: According to their habit, with equity and of their own, for there will no longer be wicked people in the world, who will rob them.] Our Rabbis expounded כְּדָבְרָם to mean: According to all that was spoken regarding them, [i.e.,] the consolations spoken for them. and...the ruins of the fat ones the houses of the wicked, who are fat. sojourners shall eat The righteous, who are like sojourners, shall eat them. fat Heb. מֵחִים, meaning “fat,” as (Psalms 66: 15): “Burnt offerings of fatlings will I offer up.”