Superstitions

My father commands that I fold one corner of my musalla after using it. He believes that Jinn will read Salaah on it and I will be harmed if I interrupt their Salaah. I have respectfully tried showing him that this is incorrect. However, he does not want to accept. He said he learnt this from his mother, hence it must be right. I do not want to show him the ruling that appears in Bahisti Zewar on the same; I fear that he may say something dangerous in a state on anger.

1. Is it necessary to follow his command in this matter?

2. If so, can I disobey it when he will not have any knowledge about it? Like if he is not around, for example.