Exodus 19:24

לך רד GO, GO DOWN and warn them a second time. God said this, because the rule is that one admonishes a person before an action is to be done and then one again admonishes him at the very moment when the action is to be done (cf. (Mekhilta). ועלית אתה ואהרן עמך והכהנים AND THOU SHALT COME UP, THOU AND AARON WITH THEE AND THE PRIESTS — One might think that they (the priests) shall also be with thee! Therefore it states “and thou shalt come up”. Consequently you must now admit that this is what God spake to him: thou hast a designated place for thyself, and Aaron a designated place for himself and they a designated place for themselves — Moses approached closer than Aaron and Aaron closer than the priests — but let the people under no circumstances break down their position to go up to the Lord (Mekhilta). פן יפרץ בם LEST HE BURST FORTH UPON THEM — Although it (the word יִפְרָץ) is punctuated with a Chataf Kametz (our Kamets Chataf — short Kametz), it has not departed from its normal grammatical form, for thus is the way of every word which has the vowel Melopum (our חולם) in its hit syllable, that being a closed syllable: when it comes with a Makkef (a hyphen) after it the vowelling is changed to a Chataf Kametz (our short Kametz).

וַיֹּ֨אמֶר אֵלָ֤יו יְהֹוָה֙ לֶךְ־רֵ֔ד וְעָלִ֥יתָ אַתָּ֖ה וְאַהֲרֹ֣ן עִמָּ֑ךְ וְהַכֹּהֲנִ֣ים וְהָעָ֗ם אַל־יֶֽהֶרְס֛וּ לַעֲלֹ֥ת אֶל־יְהֹוָ֖ה פֶּן־יִפְרׇץ־בָּֽם׃

And the Lord said to him. Go, get thee down, and thou shalt come up, thou, and Aharon with thee: but let not the priests and the people break through to come up to the Lord, lest he break forth upon them.