298. Interrupting Shemoneh Esrei

Tefillah u’Birkas Kohanim 6:8

One who is studying Torah when the time for davening arrives must stop and daven. If he learns Torah full-time for a living and he is doing so when the time for davening arrives, he need not stop since the mitzvah of Torah study is greater than the mitzvah of prayer. A person who is occupied with the welfare of the community is like a person involved in Torah study.

Tefillah u’Birkas Kohanim 6:9

One not permitted to interrupt his Shemoneh Esrei unless his life is in jeopardy. Even if the king of Israel were to greet him, he would not be permitted to reply. However, one may interrupt to reply to a non-Jewish king out of concern that the king may feel slighted and have him executed. If a person is davening Shemoneh Esrei and he sees a non-Jewish king or other despot approaching, he should shorten his prayer. If he is not able to do so, he may stop. Similarly, if one sees lethal snakes or scorpions approaching him, he should stop davening and run away. If they are not lethal, he should not stop.