My Young Children pray, but My Wife Refuses to pray
Question :
My young children, the oldest of whom is not yet three years stand behind me when I pray in the house; and I do so in order to teach them how to pray, and this is without them performing Wudhu'. Is this permissible? And what should I do regarding my wife, who is sometimes negligent in the performance of her prayers?
Answer:
The answer to the first part of the question is that it is permissible for a person to teach his children the prayer, both by word and example. This is why, when the pulpit was made for the Prophethe ascended it and began to pray on it, and when he wanted to prostrate, he descended from it and prostrated on the ground, then he said:
"I only did this in order that you follow my example and that you learn my prayer.
He should also teach them how to make Wudhu', so long as they understand. However, I do not think that children of the age mentioned by the questioner, that is, the eldest of them being three years of age, understand what is required. And the Prophet commanded us to order our children to pray from the age of seven years and to beat them if they do not pray by the time they are ten years old.
As for the answer to the second part of the question, which is that the wife does not pray, the answer is that it is upon the husband to command her to pray and to discipline her therein; but if she insists upon not praying, in that case, she will be a disbeliever - we seek refuge with Allah from that - and in this case the marriage will be annulled and she will not be permissible to him so long as she abandons prayer, because Allah, the Most High says:
Then if you ascertain that they are true believers, send them not back to the disbelievers. They are not (lawful) wives for the disbelievers, nor are the disbelievers lawful (husbands).
So it is not permissible for a Muslim to marry a disbelieving renegade from Islam; and should this apostasy take place after the marriage, then the marriage is annulled, then if she returns to Islam before the expiry of her 'Iddah then she will (still) be his wife, but if not, then she must part from him.
Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 2 Pages 219-220