Malbim Ayelet HaShachar Klal 494
Can copy this into an AI, or connect the whole library to your assistant. For deeper learning, you can directly use the original seforim, sites, and apps.
שם "שפתים" בא תמיד בריבוי הזוגיי. ושם "שפם" בא על עת שבולם שפתיו מלדבר כגון בעת האבל. (תזריע קנד)
Ayelet Hashachar, translated by Betzalel Avraham Feinstein, 2021
The noun שפתים (lips) always comes in plural, since they come in pairs. And the noun שפם (upper lip) comes in a time in which one’s lips are restrained from speaking, for example in a time of mourning.