if a man wants to marry third time then what is its rule.can he marry by the permission of only one wife.and is it compulsory to take written permission.
there is no such law in Islam to take written permission from 1st or 2nd wife . It's the man made law applied in some Muslim majority countries .
In Islam , The condition for taking more than one wife is hubby must act with them Justly and Allah Knows best.
"Marry women of your choice, two, or three, or four; but if you fear that you shall not be able to deal justly (with them), then only one." Al-Qur�an (4:3)