What is the ruling on someone who prays in the mosque, then comes to his family and leads them in prayer?

There is no harm for one who prays in the mosque and returns to his family to lead them in prayer, for it is authentically reported in the Two Sahihs that Mu'adh ibn Jabal used to pray 'Isha with the Messenger of Allah, Allah's blessings and peace be upon him, then return to his people and lead them in that prayer.