וְהַמִּצְפָּה֙ אֲשֶׁ֣ר אָמַ֔ר יִ֥צֶף יְהוָ֖ה בֵּינִ֣י וּבֵינֶ֑ךָ כִּ֥י נִסָּתֵ֖ר אִ֥ישׁ מֵרֵעֵֽהוּ׃
and Mizpah, for he said: ‘The LORD watch between me and thee, when we are absent one from another.
Read kabbalistic (mystical) interpretation of Genesis 31:49: and classical mystical sources.