大比丘三千威儀 1.78

1.78

住有五事：一者當於外彈指、二者入當脫帽、三者當作禮、四者當正住人教坐乃坐、五者不得忘持入經。

There are five matters regarding remaining there: first, one must snap one's fingers outside; second, upon entering, one must remove one's cap; third, one must pay homage; fourth, one must stand upright and sit only after being told to sit; fifth, one must not forget to bring in the sūtras.