שִׁיתָ֣ה יְ֭הוָה שָׁמְרָ֣ה לְפִ֑י נִ֝צְּרָ֗ה עַל־דַּ֥ל שְׂפָתָֽי׃
Pon, oh SEÑOR, guarda á mi boca: Guarda la puerta de mis labios.
Rashi on Psalms
O Lord, place a guard for my mouth when I pray before You, that I should speak poetically, that it should be acceptable.
Rashi on Psalms
the portal of my lips That is the upper lip (like portals of my lips).