Flog a dead horse and Harp on

Harp on and flog a dead horse are semantically related. in dwell on topic. In some cases you can use "Harp on" instead a verb phrase "Flog a dead horse".

Harp on verb - To speak or write about insistently and usually tiresomely.

Flog a dead horse and harp on are semantically related. You can use "Flog a dead horse" instead a verb "Harp on".