Is it permissible to pray supererogatory prayers, such as the night prayer (Qiyam al-Layl), in congregation with the aim of gathering people to teach them matters of their religion and introduce them to the Sunnah of the Messenger (peace be upon him)?

Congregational prayer is permissible for supererogatory prayers (nafl), such as the night vigil (qiyam al-layl), especially if it leads to benefits like instructing Muslims in matters of their religion, provided that it is not performed regularly, out of fear of falling into the category of an innovated addition (bid'ah idafiyyah).