Rashi on TanakhPsalms 43

Avenge me Heb. שפטני, lit. judge me.

against an unkind nation That is Ishmael, who dwelt between two righteous men [Abraham and Isaac] and did not learn from their deeds.

Send Your light and Your truth The King Messiah, who is compared to light, as it is stated (below 132:17): “I have set up a lamp for my anointed,” and Elijah the prophet, who is true, a faithful prophet.

that they may lead me Heb. ינחוני, menoront moi in old French, they shall lead me.

to the God To the Holy One, blessed be He, who is the joy of my exultation.

and I will thank You with a lyre because You took me out of my exile.