Variantly: "Your right hand, O L–rd, is grand in power. Your right hand" — twice. When Israel do the will of the L–rd, they, as it were, convert the "left" to the "right." And when they do not do the will of the L–rd, they convert the "right" to the "left," viz. (Eichah 2:3) "He has turned back His right hand before the foe."
When Israel Does the Will of God, They Convert the Left to the Right
Mekhilta Tractate Shirah 5:12