Q. A person who came from the asara rishonim, may he leave to wake someone up for Shacharis, or will he lose the status of being from the asara rishonim? May one leave to get a drink of water, etc, or only for tzorchei tefilla?
A. Horav Shlomo miller’s Shlit’a opinion is that it depends if one was present at the beginning of the tefilah. before he left temporarily. If he was, he is considered as one of the asara rishonim or first ten.
That beginning may differ from shul to shul. In some it may be when they start saying brochos or ma tovu aloud. In others it may be a kaddish recitation. In some shuls. when there is a shiur before davening or people learn then privately, they usually stop at the beginning of davening. that could be considered the starting of the tefila.
The Rov added, that the above applies, only when one leaves after there is already a minyan that he also was instrumental in bringing the Shechina to.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a