וְזָרְחָ֨ה לָכֶ֜ם יִרְאֵ֤י שְׁמִי֙ שֶׁ֣מֶשׁ צְדָקָ֔ה וּמַרְפֵּ֖א בִּכְנָפֶ֑יהָ וִֽיצָאתֶ֥ם וּפִשְׁתֶּ֖ם כְּעֶגְלֵ֥י מַרְבֵּֽק׃
But unto you that fear My name shall the sun of righteousness arise with healing in its wings; and ye shall go forth, and gambol as calves of the stall.
Rashi on Malachi
and be fat an expression of fat, as in (Jer. 50: 11), “as you become fat, like a threshing heifer.”
Rashi on Malachi
as fatted calves [the calves] that enter the team to be fattened; kopla, cople in Old French: animals tied together.