Ruling on teaching the second wife’s children on the first wife’s day

Praise be to Allah.

We put this question to Shaykh Muhammad ibn Saalih al-‘Uthaymeen, may Allaah preserve him, who answered as follows:

“This is not allowed, it is haraam.”

Question:

But the children need to be taught.

Answer:

“He should bring them to the house of the wife whose day it is. And Allaah knows best.”