What is the ruling on writing a supplication with water and saffron and hanging it on a tree, and is there shirk in the text of the supplication?

It is permissible to write supplications with saffron, as reported by some scholars. However, what the questioner mentioned about placing the writing on a tree indicates that the man is a charlatan, and he might be dealing with jinn or performing a love charm, which is forbidden in Islamic law. Furthermore, the mentioned supplication is impermissible because it constitutes an aggression in supplication by supplicating against the man. It would have been more appropriate for the woman to supplicate for herself for marriage to someone whose religion and character are pleasing, and to leave the matter to Allah to choose for her.