וַיִּרְאוּ֙ כָּל־הָ֣עֵדָ֔ה כִּ֥י גָוַ֖ע אַהֲרֹ֑ן וַיִּבְכּ֤וּ אֶֽת־אַהֲרֹן֙ שְׁלֹשִׁ֣ים י֔וֹם כֹּ֖ל בֵּ֥ית יִשְׂרָאֵֽל׃ (ס)
And when all the congregation saw that Aaron was dead, they wept for Aaron thirty days, even all the house of Israel.
Read halakhic rulings (Jewish law) on Numbers 20:29: and classical halakhic sources.