If on Shabbos one began to say the weekday shemoneh esrei:
- If by Maariv, Shacharis or Minchah, conclude the berachah, and then continue with the correct shemoneh esrei.
- If by Mussaf, stop immediately, and then start “tikanta Shabbos.”
- If one only said the word one word “atta” (but did not say the next word “chonein”):
- If by Maariv or Minchah, continue with the correct shemoneh esrei (“atta kidashta” or “atta echad”).
- If by Shacharis:
- if it was a slip of the tongue, but one intended to say the Shabbos shemoneh esrei, stop immediately and say “Yismach Moshe.”
- If one absent-mindedly thought it was a weekday, conclude the current beracha “atta chonein,” and then continue “Yismach Moshe.”
- If by Mussaf, stop immediately and say “Tikanta Shabbos.”