בְּאַרְבָּעָ֣ה עָשָֽׂר־י֠וֹם בַּחֹ֨דֶשׁ הַזֶּ֜ה בֵּ֧ין הָֽעֲרְבַּ֛יִם תַּעֲשׂ֥וּ אֹת֖וֹ בְּמוֹעֲד֑וֹ כְּכָל־חֻקֹּתָ֥יו וּכְכָל־מִשְׁפָּטָ֖יו תַּעֲשׂ֥וּ אֹתֽוֹ׃
In the fourteenth day of this month, at dusk, ye shall keep it in its appointed season; according to all the statutes of it, and according to all the ordinances thereof, shall ye keep it.’
Read Kabbalistic (mystical) interpretations of Numbers 9:3: Zohar and classical Jewish mystical sources, free online.