שָׁלֹ֥שׁ פְּעָמִ֖ים בַּשָּׁנָ֑ה יֵרָאֶה֙ כָּל־זְכ֣וּרְךָ֔ אֶת־פְּנֵ֛י הָֽאָדֹ֥ן ׀ יְהוָ֖ה אֱלֹהֵ֥י יִשְׂרָאֵֽל׃
Three times in the year shall all thy males appear before the Lord GOD, the God of Israel.
Read kabbalistic (mystical) interpretation of Exodus 34:23: and classical mystical sources.