How does one who has already prayed the obligatory prayer (Dhuhr) pray with another person who wishes to pray Dhuhr in congregation? Should he be the Imam or a follower, and is it permissible for him to sit for the first tashahhud with the other person, given that his prayer is a supererogatory one?

It is permissible for a person to pray in congregation a second time after having already performed the obligatory prayer in congregation, in order to give charity to someone who missed the congregational prayer. This applies whether the one giving charity acts as the imam or as a follower. It is preferable for the one who has already performed the obligatory prayer to lead the prayer as imam, to avoid disagreement. The follower must follow the imam in all actions of the prayer and sit for the first tashahhud.