עוּרִ֨י עוּרִ֤י לִבְשִׁי־עֹז֙ זְר֣וֹעַ יְהוָ֔ה ע֚וּרִי כִּ֣ימֵי קֶ֔דֶם דֹּר֖וֹת עוֹלָמִ֑ים הֲל֥וֹא אַתְּ־הִ֛יא הַמַּחְצֶ֥בֶת רַ֖הַב מְחוֹלֶ֥לֶת תַּנִּֽין׃
Awake, awake, put on strength, O arm of the LORD; Awake, as in the days of old, The generations of ancient times. Art thou not it that hewed Rahab in pieces, That pierced the dragon?
Read Kabbalistic (mystical) interpretations of Isaiah 51:9: Zohar and classical Jewish mystical sources, free online.