The obligatory prayer in the mosque and the voluntary prayer at home with the wife

Question:
A man prays the obligatory prayer in the mosque, then returns and prays the voluntary prayer at home, where his wife comes and prays with him intending the obligatory prayer, while he intends the voluntary prayer. Is their action valid, even if done on a regular basis?

Answer:
As for his praying the obligatory prayer in the mosque and the voluntary prayer at home, that is good. This is because the Prophet (peace and blessings be upon him) commanded that voluntary prayers be performed in the homes, as this keeps one away from showing off in worship and also leads to the houses being filled with worship. He (peace and blessings be upon him) said: So one should pray the voluntary prayers at home. The Prophet (peace and blessings be upon him) used to pray the voluntary prayers in his home, and he would only go out to pray the obligatory prayers in the mosque, peace and blessings be upon him. The best prayer of a man is in his home, except for the obligatory prayer.
And as for his wife praying with him intending it to be the obligatory prayer while he intends it to be the voluntary prayer, there is no harm in that. It is permissible for the one praying the obligatory prayer to follow the one praying the voluntary prayer, according to the correct opinion. Just as Mu'adh used to pray with the Prophet (peace and blessings be upon him) and then go out and pray with his people; for him it was a voluntary prayer and for them it was an obligatory one. It is permissible for the one praying the obligatory prayer to follow the one praying the voluntary prayer, according to the correct opinion of the scholars. But his wife should not pray beside him; she should not stand beside him, but rather behind him; because the position of the woman is behind the man. A woman does not form a row with a man, even if it is her husband, or her brother, or her mahram; she does not stand beside him, but rather behind him; because the position of the woman is behind the man or men in prayer. Yes.