שְׁמַ֤ע אֵלַי֙ יַֽעֲקֹ֔ב וְיִשְׂרָאֵ֖ל מְקֹרָאִ֑י אֲנִי־הוּא֙ אֲנִ֣י רִאשׁ֔וֹן אַ֖ף אֲנִ֥י אַחֲרֽוֹן׃
Hearken unto Me, O Jacob, And Israel My called: I am He; I am the first, I also am the last.
Read kabbalistic (mystical) interpretation of Isaiah 48:12: and classical mystical sources.