If at Shabbos Maariv, Shacharis, or Mincha, the person started the wrong Shabbos shemoneh esrei:
- If he remembered before saying HaShem’s name at the conclusion of the beracha mekadesh haShabbos, he should stop and start with the right one.
- If after, he should just continue (unless he said the mussaf nussach).
- If he said the mussaf nussach, stop immediately wherever you are, and continue with the right shemoneh esrei.
If at mussaf the person began to say the wrong Shabbos shemoneh esrei:
- If before mekadesh haShabbos,or after he finished the berachah of retzei, stop immediately and start tikanta Shabbos.
- If right after he said mekadesh haShabbos, say the words: venaaseh lefanechoh temidei hayom vekorban mussaf,and continue with retzei.
- If in the middle of retzei, say vehasheiv ess hoavodah lidevir baisecha,venaaseh lefanechoh temidei hayom vekorban mussaf, v’ishei Yisrael utefillasahm…