וַיִּקְרָ֖א אַרְיֵ֑ה עַל־מִצְפֶּ֣ה ׀ אֲדֹנָ֗י אָנֹכִ֞י עֹמֵ֤ד תָּמִיד֙ יוֹמָ֔ם וְעַל־מִ֨שְׁמַרְתִּ֔י אָנֹכִ֥י נִצָּ֖ב כָּל־הַלֵּילֽוֹת׃
And he cried as a lion: ‘Upon the watch-tower, O Lord, I stand continually in the daytime, And I am set in my ward all the nights.’
Read midrashic interpretation of Isaiah 21:8: and classical rabbinic exegesis.