רְאוּבֵן֙ בְּכֹ֣רִי אַ֔תָּה כֹּחִ֖י וְרֵאשִׁ֣ית אוֹנִ֑י יֶ֥תֶר שְׂאֵ֖ת וְיֶ֥תֶר עָֽז׃
Reuben, thou art my first-born, My might, and the first-fruits of my strength; The excellency of dignity, and the excellency of power.
Read kabbalistic (mystical) interpretation of Genesis 49:3: and classical mystical sources.