Is it permissible to go out with an ex-husband who does not pray – accompanied by their children – in public places for the purpose of the children meeting both their parents, and is his spending on them unlawful?

If a man divorces his wife with a final, irrevocable divorce (the third divorce) or with one divorce whose waiting period has expired, she becomes a stranger to him. It is not permissible for him to be alone with her, or to touch her, or to look at her. His relationship with her is like his relationship with any other strange woman. The presence of children does not justify such actions. As for accepting maintenance for the children from the divorced father, it is permissible even if he does not pray. You should remind your children to advise him to pray.