Rashi on Exodus 15:6/רש"י על שמות ט״ו:ו׳

1ימינך ... ימינך THY RIGHT HAND — twice! — When Israel performs the will of the Omnipresent the left hand (intended for punishment) becomes a right hand (bestowing reward, so that God has two right hands as it were) (Mekhilta).

2ימינך ה' נאדרי בכח THY RIGHT HAND, O LORD, IS GLORIOUS IN POWER to deliver Israel, and thy second right hand dashes the enemy in pieces. But it seems to me that if we have to take it in the sense: Thy right hand is glorious to save, thy right hand dashes in pieces etc. the explanation is that the self-same right hand itself dashes the enemy in pieces, something which it is impossible for a human being — to do two actions with one hand. But the literal sense of the text is: “Thy right hand, that is glorious in power — what does it do?” — “Thy right hand, O Lord, dashes the enemy in pieces”. There are many Scriptural verses exactly in this poetical form, e. g., (Psalms 92:10) “For, behold, thine enemies, O Lord, for behold, thine enemies shall perish” and others similar.

3נאדרי The י is redundant as in (Lamentations 1:1) “full of (רבתי) people . . . princess (שרתי) amongst the provinces”; (Genesis 31:39) “stolen (גנבתי) by day”.

4תרעץ אויב means, it always crushes and shatters the enemy; similar in meaning to it is, “And they crushed (וירעצו) and broke the children of Israel”, in the Book of Judges (Judges 10:8). [Another explanation is: Thy right hand that is glorious in power shatters and punishes the enemy, and these words must be connected with the following: