A priest must not enter the sanctuary of the Temple indiscriminately

The LORD said to Moses: "Tell your brother Aaron that he shall not enter at any time into the holy place inside the veil, before the mercy seat which is on the ark, or he will die; for I will appear in the cloud over the mercy seat.

Hebrew

ב וַיֹּאמֶר יְהוָה אֶל-מֹשֶׁה, דַּבֵּר אֶל-אַהֲרֹן אָחִיךָ, וְאַל-יָבֹא בְכָל-עֵת אֶל-הַקֹּדֶשׁ, מִבֵּית לַפָּרֹכֶת--אֶל-פְּנֵי הַכַּפֹּרֶת אֲשֶׁר עַל-הָאָרֹן, וְלֹא יָמוּת, כִּי בֶּעָנָן, אֵרָאֶה עַל-הַכַּפֹּרֶת.

Greek

2 καὶ εἶπεν κύριος πρὸς Μωυσῆν Λάλησον πρὸς Ααρων τὸν ἀδελφόν σου καὶ μὴ εἰσπορευέσθω πᾶσαν ὥραν εἰς τὸ ἅγιον ἐσώτερον τοῦ καταπετάσματος εἰς πρόσωπον τοῦ ἱλαστηρίου, ὅ ἐστιν ἐπὶ τῆς κιβωτοῦ τοῦ μαρτυρίου, καὶ οὐκ ἀποθανεῖται· ἐν γὰρ νεφέλῃ ὀφθήσομαι ἐπὶ τοῦ ἱλαστηρίου.

• Parashah: Acharei Mot
• Sefer HaChinuch: 184
• Mishneh Torah: Service — Entry into the Temple

• Leviticus 16:2

Enumeration and classification from BibleData. The Greek is the Septuagint reading of the same verse, carried by the source for comparison.