Watchmen

The idea of sentinel watchmen is very ancient.

On your walls, O Jerusalem, I have appointed watchmen; all day and all night, they shall never be silent; those who remind the Lord, be not silent.		ועַל־חֽוֹמֹתַ֣יִךְ יְרֽוּשָׁלִַ֗ם הִפְקַ֙דְתִּי֙ שֹֽׁמְרִ֔ים כָּל־הַיּ֧וֹם וְכָל־הַלַּ֛יְלָה תָּמִ֖יד לֹ֣א יֶֽחֱשׁ֑וּ הַמַּזְכִּירִים֙ אֶת־יְהֹוָ֔ה אַל־דֳּמִ֖י לָכֶֽם:
And give Him no rest, until He establishes and until He makes Jerusalem a praise in the land.		זוְאַל־תִּתְּנ֥וּ דֳמִ֖י ל֑וֹ עַד־יְכוֹנֵ֞ן וְעַד־יָשִׂ֧ים אֶת־יְרֽוּשָׁלִַ֛ם תְּהִלָּ֖ה בָּאָֽרֶץ: