Maaseh Rav Siman 30
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.
א"א ובתורתך כתוב לאמר שמע ישראל כו' קודם ישתבח כי צריך להיות מן ויושע עד ה' ימלוך ח"י שמות ומן אז ישיר עד ישתבח ג"כ ח"י שמות ואין להוסיף:
Sefaria Community Translation
Do not say "and in your Torah it is written to say 'Hear O Israel...'" before Yishtabach, because there should be from 'and he saved' until 'Hashem reigns' 18 mentions of G-d's name, and from 'Az Yashir' until 'Yishtabach' also 18 names and no more.