וְהָיָ֗ה בַּיּוֹם֮ אֲשֶׁ֣ר תַּעַבְר֣וּ אֶת־הַיַּרְדֵּן֒ אֶל־הָאָ֕רֶץ אֲשֶׁר־יְהוָ֥ה אֱלֹהֶ֖יךָ נֹתֵ֣ן לָ֑ךְ וַהֲקֵמֹתָ֤ לְךָ֙ אֲבָנִ֣ים גְּדֹל֔וֹת וְשַׂדְתָּ֥ אֹתָ֖ם בַּשִּֽׂיד׃
And it shall be on the day when ye shall pass over the Jordan unto the land which the LORD thy God giveth thee, that thou shalt set thee up great stones, and plaster them with plaster.
Read kabbalistic (mystical) interpretation of Deuteronomy 27:2: and classical mystical sources.