Maaseh Rav Siman 115
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.
תפלת ערבית אפי' בשבת בזמנה דוקא ואף ביחיד אם אי אפשר במנין עשרה:
Sefaria Community Translation
The evening prayer should be prayed, even on Shabbos, in its time exactly and by oneself if he is unable to have a quorum of ten.