in his coming and in his going
At the time he arrived at a place and at the time he left it.
("And it shall be upon Aaron to minister; and its sound shall be heard when he enters the holy place before the LORD and when he goes out, so that he will not die" - Exodus 28:35)
Translation
Expression (Hebrew)
בְּבוֹאוֹ וּבְצֵאתוֹ
Definition (Hebrew)
בָּעֵת שֶׁהִגִּיעַ לְמָקוֹם וּבָעֵת שֶׁהָלַךְ מִמֶּנּוּ.
("וְהָיָה עַל אַהֲרֹן לְשָׁרֵת וְנִשְׁמַע קוֹלוֹ בְּבֹאוֹ אֶל הַקֹּדֶשׁ לִפְנֵי ה' וּבְצֵאתוֹ וְלֹא יָמוּת"- שְׁמוֹת כֹּחַ לָהּ)