וְאַחַ֤ר הַדֶּ֙לֶת֙ וְהַמְּזוּזָ֔ה שַׂ֖מְתְּ זִכְרוֹנֵ֑ךְ כִּ֣י מֵאִתִּ֞י גִּלִּ֣ית וַֽתַּעֲלִ֗י הִרְחַ֤בְתְּ מִשְׁכָּבֵךְ֙ וַתִּכְרָת־לָ֣ךְ מֵהֶ֔ם אָהַ֥בְתְּ מִשְׁכָּבָ֖ם יָ֥ד חָזִֽית׃
And behind the doors and the posts Hast thou set up thy symbol; For thou hast uncovered, and art gone up from Me, Thou hast enlarged thy bed, And chosen thee of them Whose bed thou lovedst, Whose hand thou sawest.
Read Kabbalistic (mystical) interpretations of Isaiah 57:8: Zohar and classical Jewish mystical sources, free online.