Charles H. Spurgeon on Psalms 89:25

I will set his hand also in the sea, and his right hand in the rivers. That is, he should reign from the Mediterranean to the Euphrates; figuratively expressed by his left hand being extended to the sea, and his right hand to the rivers. A similar expression is used, according to Curtius, by the Scythian ambassadors to Alexander. "If", said they, "the gods had given thee a body as great as thy mind, the whole world would not be able to contain thee. Thou wouldst reach with one hand to the east, and with the other to the west." —Kitto's Pictorial Bible.