I don't have the definitive history of "hand on the plow" song..it was always my understanding that this was an old spiritual and Pete Seeger wrote the "eyes on the prize" line...if people whose song it was prefer it then great, ..but it seems to have stripped 99% of the beauty and meaning of the oriignal song clean away. To each his or her own. Anyway, here is a google search..

http://www.google.com/search?q=keep+your+hand+on+the+plow