Rock. Omit "He is", and read "The Rock, His work is perfect". Used of Jehovah in this song five times (the number of Grace. See App-10), verses: Deu_32:4, Deu_32:15, Deu_32:18, Deu_4:30, Deu_4:31. Used twice in irony (App-6), verses: Deu_32:31, Deu_32:37. Compare 2Sa_22:31, 2Sa_22:32.